Resource selection method in vehicle to everything communication and apparatus therefore

ABSTRACT

Embodiments of the present disclosure provide a resource selection or reselection method by a user equipment (UE) and the UE in Vehicle to vehicle/pedestrian/infrastructure/network (V2X) communication. The method comprises the steps of: detecting physical sidelink control channel (PSCCH) transmitted by other UE(s); selecting (a) single-subframe resource(s) from single-subframe resources which do not overlap with single-subframe resources reserved by the detected PSCCH; and transmitting physical sidelink shared channel (PSSCH) on the selected single-subframe resource(s).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 National Stage of International ApplicationNo. PCT/KR2018/003478, filed Mar. 23, 2018, which claims priority toChinese Patent Application No. 201710182401.7, filed Mar. 24, 2017,Chinese Patent Application No. 201710304754.X, filed May 3, 2017,Chinese Patent Application No. 201710486403.5, filed Jun. 23, 2017,Chinese Patent Application No. 201710488679.7, filed Jun. 23, 2017,Chinese Patent Application No. 201710682189.0, filed Aug. 10, 2017,Chinese Patent Application No. 201711059732.8, filed Nov. 1, 2017,Chinese Patent Application No. 201711160446.0, filed Nov. 20, 2017, andChinese Patent Application No. 201810036887.8, filed Jan. 15, 2018, thedisclosures of which are herein incorporated by reference in theirentirety.

BACKGROUND 1. Field

The present disclosure generally relates to communication technology,and more particular, to a resource selection or reselection method and auser equipment (UE) performing the same in vehicle to every (V2X)communication, and to a resource allocation method and apparatus insidelink communications with low delay and high reliability.

2. Description of Related Art

In the 3rd generation partnership project (3GPP) standard, adevice-to-device direct communication link is referred to as a sidelink.Similar to uplink and downlink, there is also control channel and datachannel in sidelink, and the former is referred to as Physical SidelinkControl CHannel (PSCCH), and the latter is referred to as PhysicalSidelink Shared CHannel (PSSCH). The PSCCH is used to indicatetime/frequency domain resource positions, modulation and coding mode,and priorities of data carried in PSSCH of PSSCH transmission, whilePSSCH is used to carry data.

Control information and data in Vehicle toVehicle/Pedestrian/Infrastructure/Network or Vehicle to Everything (V2X)can be transmitted via sidelink, and at this time, the V2X communicationcomprises two transmission modes, i.e. transmission mode 3 (Mode 3) andtransmission mode 4 (Mode 4). With regard to Mode 3, transmissionresource of PSCCH and PSSCH of one UE (referred to a V2X UE, the samebelow) is both allocated by an evolved Node B (eNB), and the UEdetermines transmission resource of the PSCCH and the PSSCH by receivinga sidelink resource allocation indication transmitted by the eNB via aphysical downlink control channel (PDCCH) or an Enhanced PDCCH (EPDCCH).However, in Mode 4, the transmission resource of the PSCCH and the PSSCHare selected autonomously by the UE according to channel detectionresults. During the channel detection process, the UE first determinestime frequency resource position and priorities of scheduled PSSCH byreceiving PSCCHs transmitted by other UEs, and then further detectsdemodulation-reference signal received power of scheduled PSSCH(PSSCH-RSRP), and excludes the resource with PSSCH-RSRP higher than aparticular threshold; and the UE then calculates average received energy(S-RSSI) of the remaining resource, and at last randomly selects oneresource from those with the lowest S-RSSI as transmission resource.

In the Rel-14 3GPP standard, whether the UE uses Mode 3 or Mode 4 isconfigured according to resource pool. In order to ensure that timefrequency resource allocated to UE which uses Mode 3 is not interferedby other UEs, Mode 3 resource pool and Mode 4 resource pool should bemutually orthogonal. However, since the resource pool is semi-staticallyconfigured, while number of UEs using a certain resource pool isdynamically changed, if resource in the resource pool and number of UEswhich use the resource pool are inharmonious, then resource waste ordeficiency in the resource pool may be caused. Therefore, configuring aplurality of resource pools is not beneficial to improving theutilization efficiency of time frequency resource, and at the same timemay also negatively impact the performance of a V2X system.

It can be seen from the above analysis that in view of resourceutilization efficiency and V2X system performance, UEs of Mode 3 andMode 4 should be able to work in the same resource pool; however, inthis case, there is still no effective technical solution regarding howto effectively avoid or reduce mutual interference between UEs which useMode 3 and Mode 4 by far.

In Mode 3, the transmission resources for the PSCCH and PSSCH of one UE(referred to V2X UE in the present disclosure) are both allocated by aneNodeB (shortened as eNB in the following). The UE may determine thetransmission resources of the PSCCH and the PSSCH through receiving thesidelink resource allocation indication transmitted by the eNB via thePDCCH or EPDCCH. In Mode 4, however, the transmission resources of thePSCCH and PSSCH may be selected by the UE according to a channeldetection result. If a UE in Mode 4 has V2X data to be transmitted insubframe n (e.g., the V2X data packet arrives at a UE radio access layerno later than subframe n), and a resource selection or reselectioncondition is met, the UE determines time-frequency resources in aresource selection window [n+T1, n+T2] on current working carrier ascandidate single-subframe resources (values of T1 and T2 are determinedby the UE, but should meet T1=4, 20≤=T2≤=100), then the UE determinesavailable candidate single-subframe resources in the resource selectionwindow. During the process of determining the available candidatesingle-subframe resources, the UE firstly determines the time-frequencyresource positions and priority of a scheduled PSSCH of another UEthrough receiving the PSCCH transmitted by the another UE. Then, the UEdetects a reference signal receiving power of the scheduled PSSCH(PSSCH-RSRP), and excludes the resources whose PSSCH-RSRP is higher thana predefined threshold (referred to as resource selection step 2 in thefollowing). Further, the UE calculates an average Sidelink-ReceivingSignal Strength Indicator (S-RSSI) of the remaining resources, the X %single-subframe resources with the lowest S-RSSI are determined as theavailable candidate single-subframe resources (hereinafter referred toas resource selection step 3). In 3GPP Rel-14 specifications, the valueof X is 20. It should be noted that, the X % refers to the proportion ofthe available candidate single-subframe resources to all single-subframeresources in the resource selection window. The UE may randomly selectone of the available candidate single-subframe resources as thetransmission resource.

In the V2X communications, the data transmitted by one UE is meaningfulfor merely receiving UEs within a certain range. The range is related tothe moving speed of the transmitting UE and the receiving UE, as well asservice type of the transmitted data. In the current V2X communicationmechanism based on LTE system architecture, data successful receivingrate within the valid distance (i.e., data reliability) can reach 95% atmost. This reliability is able to meet requirement of basic securityservices. However, in application scenarios newly defined by the 3GPPsuch as platooning, advance driving and extended sensor, there is ahigher requirement for the data receiving reliability. For example, inthe platooning scenario, the highest reliability is required to reach99.99%, and in the extended sensor scenario, the highest reliability isrequired to reach 99.999%. In addition, in the above new V2X applicationscenarios, a more rigid requirement is also proposed to the datatransmission delay, the lowest delay is required to be 10 ms and 3 ms,but the current V2X communication mechanism can merely ensure a delay of20 ms.

It can be seen from the above that, in order to support V2Xcommunications in the new application scenarios, the data transmissionreliability and data transmission delay of the V2X communicationmechanism need to be improved. However, there is no effective solutionat present.

In addition, in the V2X communication system defined by 3GPP Rel-14, theresource selection and resource reselection manner of the UE are merelyapplicable for the single-carrier working manner. In order to increasethroughput and system capacity of the V2X system, in evolved V2X definedby 3GPP Rel-15, it is proposed to support multi-carrier sidelinkcommunications. In the multi-carrier sidelink communication scenario,multiple carriers may belong to the same frequency band. The multiplecarriers in the same frequency band may have In-Band Emission (IBE)interference and half-duplex restriction. In addition, the UE mayperform transmission or receiving operations on multiple carriers of thesame frequency band using one transmission or receiving radio link,which may lead to that the number of transmission or receiving radiochains of the UE is smaller than the number of carriers supported by theUE. Since the UE may select resources or transmit data simultaneously onmultiple carriers, when the UE performs the resource selection orresource reselection, the channel status of multiple carriers may impacteach other. It can be seen that, in the multi-carrier sidelinkcommunication, when the UE performs resource selection or reselection,channel status on multiple carriers needs to be considered incombination. The resource selection and reselection manner designed forthe single carrier environment in 3GPP Rel-14 is not applicable.

SUMMARY

It can be seen from the above that, in order to support multi-carriersidelink communication, the resource selection or reselection manner ofthe UE need to be modified, so as to be applicable for the multi-carriersidelink environment. However, there is no reasonable and effectivesolution at present.

The present disclosure is designed to address at least the problemsand/or disadvantages described above and to provide at least theadvantages described below.

According to one aspect of the present disclosure, a resource selectionor reselection method performed by a user equipment (UE) in vehicle tovehicle/pedestrian/infrastructure/network or Vehicle to Everything (V2X)communication is provided, which comprises the steps of: detectingphysical sidelink control channel (PSCCH) transmitted by other UE(s);selecting single-subframe resources from single-subframe resources whichdo not overlap with single-subframe resources reserved by the detectedPSCCH; and transmitting physical sidelink shared channel (PSSCH) on theselected single-subframe resources.

According to another aspect of the present disclosure, a user equipment(UE) for performing a resource selection or reselection method invehicle to vehicle/pedestrian/infrastructure/network or Vehicle toEverything (V2X) communication is provided, which comprises: a detectionmodule, for detecting physical sidelink control channel (PSCCH)transmitted by other UE(s); a resource selection or reselection module,configured to select a single-subframe resource from single-subframeresources which do not overlap with single-subframe resources reservedby the detected PSCCH; and a transmitting module, which transmitsphysical sidelink shared channel (PSSCH) on the selected single-subframeresource.

With the above method and apparatus, interference on single-subframeresources scheduled or reserved by PSCCH resources can be betteravoided, and the utilization efficiency of time frequency resources canbe increased, and the V2X system performance can be improved.

Furthermore, in order to solve at least one of the above technicalproblems, embodiments of the present disclosure provide a new resourceallocation method, so as to effectively improve data transmissionreliability under the premise of ensuring the data transmission delay.

A resource allocation method in sidelink communications includes:

a first User Equipment (UE) determining a SideLink Grant (SLG); whereinthe SLG includes position information of M Physical Sidelink SharedChannel (PSSCH) transmission resources, the M PSSCH transmissionresources are used for M times of transmission of one Transmission Block(TB), M is a positive integer;

the first UE transmitting a PSSCH according to the determined SLG.

In some embodiments, the first UE determining the SLG includes:

the first UE determining the SLG according to one or more downlinkcontrol signaling transmitted by a base station; or

the first UE determining the SLG through performing a detection in achannel detection window.

In some embodiments, when the first UE determines the SLG according toone downlink control signaling transmitted by the base station, the onedownlink control signaling includes: positions of slots where the PSSCHtransmission resources for the second time to the M-th time transmissionare located, frequency-domain positions of the PSSCH transmissionresources for each time of transmission, and the number offrequency-domain resources contained in the PSSCH transmission resourcesfor each time of transmission; wherein the slot denotes a minimumresource unit for the first UE to transmit the PSSCH.

In some embodiments, the determining the SLG includes: taking a slotwhich is after slot n1+k and belongs to a current resource pool of thefirst UE as the slot where the PSSCH transmission resource for the firsttime transmission in the SLG is located; wherein n1 denotes an index ofa slot in which the downlink control signaling is received, k is apositive integer.

In some embodiments, the first UE determines the configuration of thecurrent resource pool according to the signaling transmitted by the basestation.

In some embodiments, when the first UE determines the SLG according tomultiple downlink control signaling of the base station, each one of themultiple downlink control signaling includes: positions of multiplePSSCH transmission resources for N times of transmission of one TB,wherein N=M, N is a positive integer.

In some embodiments, the determining the SLG comprises: for eachdownlink control signaling, taking slot n2+k as the slot where the firstPSSCH transmission resource indicated by this downlink control signalingis located; wherein n2 denotes an index of a slot in which this downlinkcontrol signaling is received, k is a positive integer.

In some embodiments, each downlink control signaling includes an indexof the downlink control signaling;

the determining the SLG includes: forming the SLG by the PSSCHtime-frequency resources indicated by continuous M/N downlink controlsignaling indexed from 0 to M/N−1.

In some embodiments, there is a binding relationship between the M PSSCHtransmission resources;

the first UE determining the SLG comprises: the first UE determining aresource pattern of the SLG according to the downlink control signalingtransmitted by the base station; or, the first UE determining a resourcepattern of the SLG according to the detection performed in the channeldetection window;

the resource pattern includes M PSSCH transmission resource units in apredefined resource pattern space, and is used for indicating theposition information of the PSSCH time-frequency resources for the Mtimes transmission of the TB; a first PSSCH transmission resource unitand a last PSSCH transmission resource unit contained in each resourcepattern have a time-domain gap less than or equal to a sum of a maximumtolerated delay for data transmission of the first UE and the timerequired for encoding the PSSCH.

In some embodiments, when the first UE determining the resource patternaccording to the downlink control signaling transmitted by the basestation, the downlink control signaling includes an index r of theresource pattern of the SLG, wherein the index of the resource patterndenotes unique index information of each resource pattern in theresource pattern space.

In some embodiments, the determining the resource pattern of the SLGincludes: the first UE determining the first resource pattern with indexof r after slot n3+k as the resource pattern of the SLG, and determiningthe resource pattern as allocated resources of the SLG; wherein n3denotes an index of a slot in which the downlink control signaling isreceived, k is a positive integer.

In some embodiments, when the PSSCH and a Physical Sidelink ControlChannel (PSCCH) scheduling the PSSCH are transmitted in the same slot,and a second UE semi-persistently occupies each PSSCH transmissionresource with a predefined time interval, the first UE determining theSLG according to the detection performed in the channel detection windowincludes:

the first UE detecting slots in the channel detection window before slotn4, wherein for each detected slot, decoding the PSCCH in the slot, anddetermining the number of successfully decoded PSCCH in the slot, andmeasuring, according to the successfully decoded PSCCH, a referencesignal receiving power and a receiving energy of the PSSCH scheduled bythe PSCCH, a priority of the data transmitted by the PSSCH, and areservation interval for the PSSCH transmission resource, the first UEmeasuring an average receiving energy of each Resource Block Group (RBG)or each Resource Block (RB) in the slot;

the first UE estimating, according to a measurement result in thechannel detection window, the number of second UEs which may transmitPSCCH in each candidate slot in the resource selection window, a PSSCHreference signal receiving power on each candidate single-slot resource,and the average receiving energy of each RBG or RB in the resourceselection window;

according to an estimated result, the first UE selecting, in allcandidate single-slot resources in the resource selection window, Msingle-slot resources on which number of resources occupied by thesecond UE is lower than a predefined condition, and determining theselected M single-slot resources as the M PSSCH transmission resourcesof the SLG; the M single-slot resources are located in different slots;

wherein n4 denotes a slot in which the SLG determining operation isperformed, the resource selection window is [n4+T₁,n4+T₂], T1 and T2 arepredefined positive integers; if the RBG is configured and the RBG is aresource allocation unit, and all PRBs in each RBG can be allocated,determining LRBG RBGs in any slot belonging to the current resource poolof the first UE and within the resource selection window as a candidatesingle-slot resource; if the RBG is configured and the RBG is a resourceallocation unit, but only one PRB with the same index in respective RBGcan be allocated, determining the i-th PRB in {tilde over (L)}_(RBG)RBGs in any slot which is belonging to the current resource pool of thefirst UE and within the resource selection window as a candidatesingle-slot resource; if the RBG is not configured, determining LRB PRBsin any slot which is belonging to the current resource pool of the firstUE and within the resource selection window as a candidate single-slotresource; LRBG, {tilde over (L)}_(RBG), and LRB are positive integers;the second UE is a UE detected by the first UE; the PRB denotes aminimum frequency resource unit for transmitting the PSSCH by the firstUE.

In some embodiments, the selecting the M single-slot resources includes:

the first UE selecting, according to the estimated result, X % slotswith minimum number of successfully decoded PSCCH in the resourceselection window as candidate slots;

the first UE excluding single-slot resources with PSSCH reference signalpower higher than a specified threshold from the single-slot resourcesof the candidate slots according to the PSSCH reference signal receivingpower and the priority of the data transmitted by the PSSCH, thespecified threshold is determined according to the priority of the datatransmitted by the PSSCH and the priority of the data to be transmittedby the first UE;

the first UE sorting remaining single-slot resources of the candidateslots according to their receiving energies, selecting M single-slotresources from Y % single-slot resources with lowest receiving energy,and taking the selected M single-slot resources as the M PSSCHtransmission resources of the SLG;

X and Y are predefined positive values.

In some embodiments, the PSCCH transmitted by the first UE indicatesonly the time-frequency resource position of the currently scheduledPSSCH, or indicate the position of the currently scheduled PSSCH and thenext PSSCH transmission, or indicate the position of M PSSCHtransmission resources for transmitting one TB at the same time.

In some embodiments, when the second UE semi-persistently occupies theresource pattern according to a predefined interval, the first UEdetermining the resource pattern of the SLG according to the detectionperformed in channel detection window includes:

the first UE detecting slots in the channel detection window before slotn4; wherein for each detected slot, the first UE decoding a PSCCH in theslot, measuring average reference signal receiving power of multiplePSSCHs on the resource pattern, priority of data transmitted by thePSSCHs and a resource pattern reservation interval according to thedecoded PSCCH, the first UE measuring an average receiving energy ofeach resource pattern in the channel detection window;

the first UE estimating, according to the measurement result in thechannel detection window, PSSCH reference signal receiving power andaverage receiving energy of each candidate resource pattern in theresource selection window;

according to an estimated result, the first UE selecting one resourcepattern from all candidate resource patterns in the resource selectionwindow as the resource pattern of the SLG;

wherein n4 denotes a slot in which the SLG determining operation isperformed, any resource pattern whose beginning subframe and endingsubframe are both within the resource selection window is taken as thecandidate resource pattern.

In some embodiments, the selecting one resource pattern includes:

according to the estimated result, the first UE excluding resourcepatterns whose PSSCH reference signal average receiving power is higherthan a second specified threshold from the candidate resource patternsof the resource selection window, the second specified threshold isdetermined according to the priority of the data transmitted by thePSSCH and the priority of the data to be transmitted by the first UE;

the first UE sorting remaining resource patterns according to theiraverage receiving energies, selecting one resource pattern from Y %resource patterns with lowest receiving energy, and taking the selectedresource pattern as the resource pattern of the SLG;

wherein Y is a predefined positive integer.

In some embodiments, the PSCCH transmitted by the first UE is used forindicating an index of the transmission resource pattern of the PSSCHscheduled by the PSCCH.

In some embodiments, after the first UE determining the SLG and beforethe first UE transmitting the PSSCH according to the determined SLG, themethod further comprises: the first UE determining an occupation mannerof the SLG;

the transmitting the PSSCH according to the determined SLG comprises:the first UE transmitting the PSSCH according to the SLG based on thedetermined occupation manner.

In some embodiments, the occupation manner includes: occupying the SLGsemi-persistently according to a predefined time interval; or occupyingthe SLG for one time.

In some embodiments, the determining the occupation manner of the SLGincludes:

when the first UE determines the SLG according to one or more downlinkcontrol signaling transmitted by the base station, the first UEdetermining the occupation manner of the SLG according to the downlinkcontrol signaling; and/or

when the first UE determines the SLG according to the detectionperformed in the channel detection window, the first UE determining theoccupation manner of the SLG according to a decision of a higher layerof the first UE.

In some embodiments, when the first UE occupies the SLGsemi-persistently according to a predefined period, the SLG furtherincludes a period length of the semi-persistent occupation; and/or

when there is no binding relationship between the PSSCH time-frequencyresources and PSCCH resources scheduling the PSSCH, the one or moredownlink control signaling include position of transmission resources ofthe PSCCH.

In some embodiments, when determining the SLG through channel detection,the first UE selects one PSCCH transmission resource according to achannel detection result.

In some embodiments, the method further includes:

the first UE determining a modulation and coding scheme for transmittingthe TB.

A resource allocation apparatus for sidelink communications includes: adetermining unit and a transmitting unit;

the determining unit is to determine a SideLink Grant (SLG); wherein theSLG includes position information of M Physical Sidelink Shared Channel(PSSCH) transmission resources, the M PSSCH transmission resources areused for M times of transmission of one Transmission Block (TB), M is apositive integer;

the transmitting unit is to transmit a PSSCH according to the determinedSLG.

It can be seen from the above technical solution that, in the presentdisclosure, the first UE is able to determine the SLG through receivingdownlink control signaling of the base station or through channeldetection, the SLG may include multiple PSSCH transmission resources fortransmitting one TB, or include a resource pattern correspondingmultiple PSSCH transmission resources used for transmitting one TB.Then, the first UE transmits PSSCH according to the SLG. According tothe method provided by the present disclosure, half-duplex impactbetween different UEs can be effectively decreased under the premise ofensuring the data transmission delay, thus the data successful receivingrate is increased.

Embodiments of the present disclosure further provide a resourceselection or reselection method and apparatus in V2X communications, soas to overcome half-duplex restriction in the multi-carrier sidelinkcommunication and reduce IBE interferences between multiple carriers.

Some embodiments of the present disclosure provide a resource selectionor reselection method in V2X communication, including:

a User Equipment (UE) determining a carrier set C available for resourceselection or reselection;

the UE determining a candidate single-subframe resource set S in thecarrier set C; and

the UE selecting at least one single-subframe resource from the set S,and transmitting a sidelink data channel on the selected resource.

In some embodiments, the carrier set C includes at least one carrier;

if the carrier set C includes at least two carriers, the configurationof Sidelink Synchronization Signal (SLSS) transmission subframes on theat least two carriers are the same;

or, if the carrier set C includes at least two carriers, theconfiguration of the SLSS transmission subframes on the at least twocarriers are different, and if subframe x is one of the SLSStransmission subframes on any of the at least two carriers, subframe xon each of the at least two carriers is not used for configuring aresource pool;

or, if the carrier set C includes at least two carriers, for each ofsome or all of the at least two carriers, the SLSS transmissionsubframes and resource pool are configured independently.

In some embodiments, the determining the candidate single-subframeresource set S in the carrier set C includes:

determining that a single-subframe resource R_(x,y) ^(c) on any carrierc in the carrier set C includes L_(subCH) ^(c) continuous sub-channelsstarting from sub-channel x in subframe t_(y) ^(SL), wherein

y denotes a relative index of subframe t_(y) ^(SL) in the resource pool;

L_(subCH) ^(c) denotes a number of sub-channels used for one PSSCHtransmission on carrier c, c=0, 1, . . . , N1−1;

if the UE performs resource selection or reselection in subframe n,L_(subCH) ^(c) continuous sub-channels in any subframe belonging to theresource pool and within [n+T₁,n+T₂] on carrier c are candidatesingle-subframe resources, wherein the determination of T1 and T2 aresubject to the implementation of the UE; a total number ofsingle-subframe resources on carrier c is denoted by M_(total) ^(c) theM_(total) ^(c) candidate single-subframe resources constitute a set Sc,a union of single-carrier single-subframe resource sets of carriers inthe carrier set C is the candidate single-subframe resource set S,wherein the single-carrier single-subframe resource is a single-subframeresource of which all subchannels are located on the same carrier.

In some embodiments, the UE selecting the at least one single-subframeresource in the set S via any one of:

the UE selecting one single-carrier single-subframe resource for datatransmission in the set S, wherein the UE randomly selecting onesingle-carrier single-subframe resource with equal probability from theset S; or, the UE randomly selecting a carrier c with equal probabilityfrom all carriers in the carrier set C, and randomly selecting onesingle-carrier single-subframe resource with equal probability from theset Sc;

the UE selecting at least two single-carrier single-subframe resourcesfor data transmission in the set S, wherein the UE randomly selectingmultiple carriers or selecting all carriers with equal probability inthe carrier set C, and randomly selecting one single-carriersingle-subframe resource with equal probability from the single-carriersingle-subframe resources of each selected carrier;

the UE selecting at least two single-carrier single-subframe resourcesfor data transmission in the set S, wherein the UE sorting the carriersin the carrier set C according to their priorities or Channel Busy Ratio(CBR), the order of the carriers is denoted by carrier 0>carrier 1> . .. >carrier N1−1, the UE randomly selecting one single-carriersingle-subframe resource with equal probability from the single-carriersingle-subframe resources of carrier 0, the subframe where the selectedsingle-carrier single-subframe resource is located is denoted by t0, ifsubframe t0 contains single-carrier single-subframe resource on carrier1, the UE randomly selecting one single-carrier single-subframe resourcefrom them with equal probability, if the subframe t0 does not containsingle-carrier single-subframe resource on carrier 1, the UE randomlyselecting one single-carrier single-subframe resource with equalprobability from a single-carrier single-subframe resource set ofcarrier 1, and the UE repeating the process to select the single-carriersingle-subframe resources on other carriers;

the UE selecting multiple single-carrier single-subframe resources fordata transmission in the set S, wherein the UE selecting at most onesingle-carrier single-subframe resource on each carrier, and indexes ofsubframes where the single-carrier single-subframe resources selected bythe UE are located have a minimum variance, if there are multipleselections with the minimum variance, the UE randomly selecting one ofthe selections;

the UE randomly selecting X1 single-carrier single-subframe resourceswith equal probability from remaining single-carrier single-subframeresources of each subset Sc of the set S, and the UE selecting mcsingle-carrier single-subframe resources for transmitting the PSSCH fromX1 single-carrier single-subframe resources selected from each set Sc,wherein c=0, 1, . . . , N1−1, and mc=0 or 1.

In some embodiments, before the UE selecting the at least onesingle-subframe resource in the set S, the method further includes: theUE excluding one or more candidate single-subframe resources from theset S according to a Physical Sidelink Control Channel (PSCCH) detectedin a channel detecting window and an average Sidelink-Receiving SignalStrength Indicator (S-RSSI) measured in the channel detecting window;

the process of the UE selecting at least one single-subframe resource inthe set S comprises: the UE selecting at least one single-subframeresource from remaining single-subframe resources in the set S.

In some embodiments, the process of the UE excluding one or morecandidate single-subframe resources from the set S according to aPhysical Sidelink Control Channel (PSCCH) detected in the channeldetecting window and the S-RSSI measured in the channel detecting windowincludes:

if the UE detects the PSCCH in subframe t_(m) ^(SL) in the channeldetection window on carrier c, c=0, 1, . . . , N1−1, and a value of apriority field in the PSCCH is prio_(RX), according to a resourcereservation indication, the PSCCH reserves the same frequency resourcein subframe

t_(m + P_(rsvp _ RX))^(SL),

and a PSSCH-Reference Signal Received Power (RSRP) measured on a PSSCHscheduled by the PSCCH is higher than a threshold Th_(prio) _(TX)_(,prio) _(RX) ^(c), wherein prio_(RX) denotes a value of a priorityfield in a subsequently transmitted PSCCH indicated by a higher layer ofthe UE, Th_(prio) _(TX) _(,prio) _(RX) ^(c) a denotes a threshold forthe PSSCH-RSRP when the value of the priority field of the subsequentlytransmitted PSCCH indicated by the higher layer of the UE is prio_(TX),whereas the measured priority of the PSCCH is prio_(RX); then:

for any single-carrier single-subframe resource R_(x,y) ^(c) in a subsetSc of the set S, if there is a variable j∈{0, 1, . . . , C_(rexel)−1}which makes the single-subframe resource R_(x,y+j×P) _(rsvp_TX) overlapwith reserved resource indicated in the PSCCH, wherein Cresel denotesthe number of times that the resource is to be reserved after resourcereselection of the UE, P_(rsvp_TX) denotes an assumed resourcereservation period for determining the available candidatesingle-subframe resource indicated by higher layer of the UE, the UEdeleting the single-subframe resource R_(x,y) ^(c) from the set Sc;

for any remaining single-subframe resource R_(x,y) ^(c) in subset Sc ofthe set S, c=0, 1, . . . , N1−1, the UE calculates an average value ofthe S-RSSI measured on subchannels x+k′ in subframe t_(y-P*j) ^(SL) inthe channel detection window, wherein j is an integer larger than 0, andk′=0, . . . , L_(subCH) ^(c)−1, P is a predetermined value and denotesan S-RSSI average period, the average value of S-RSSI is noted byE_(x,y) ^(c), the UE excluding (100−X2)% resources with highest E_(x,y)^(c) from the remaining single-subframe resources from the set Sc,wherein X2 is a predefined value.

In some embodiments, wherein the process of the UE determining thecandidate single-subframe resource set S in the carrier set C includes:

dividing the carriers in the carrier set C into at least one carriergroup, each carrier group consists of at least one carrier, the carrierset C includes R carrier groups, the number of carriers in carrier groupG is M1, wherein G=0, 1, . . . , R−1, M1≤N1, and M1>1, N1 denotes thenumber of carriers in the carrier set C, the carriers in the carriergroup G are denoted by g0, g1, . . . , gM1−1;

determining that one carrier-group single-subframe resource R_(x) _(g)_(,y) ^(G) in carrier group G includes L_(subCH) ^(g) ⁰ continuoussubchannels starting from subchannel x_(g) ₀ on carrier g0 of subframet_(y) ^(SL), L_(subCH) ^(g) ¹ continuous subchannels starting fromsubchannel x_(g) ₁ on carrier g1 of subframe t_(y) ^(SL), . . . , andL_(subCH) ^(g) ^(M1-1) continuous subchannels starting from subchannelx_(g) _(M-1) on carrier gM1−1 of subframe t_(y) ^(SL), wherein

y denotes a relative index of the subframe t_(y) ^(SL) in the resourcepool;

L_(subCH) ^(g) ¹ meets

${{\sum\limits_{i = 0}^{i = {{M\; 1} - 1}}L_{subCH}^{g_{i}}} = L},$

L is determined by a higher layer of the UE, i=0, 1, . . . , M1−1;

if the UE performs resource selection or reselection in subframe n,L_(subCH) ^(g) ⁰ , L_(subCH) ^(g) ¹ , . . . , L_(subCH) ^(g) ^(M1-1)continuous subchannels respectively on carriers g0, g1 . . . , gM1−1 inany subframe belonging to the resource pool and within [n+T₁,n+T₂] onthe carrier group G are determined as the candidate single-subframeresources, wherein the values of T1 and T2 are subject to theimplementation of the UE; a total number of single-subframe resources incarrier group G is denoted by M_(total) ^(G), the M_(total) ^(G)candidate single-subframe resources constitute the set S^(G); L_(subCH)^(g) ⁰ , L_(subCH) ^(g) ¹ , . . . , and L_(subCH) ^(g) ^(M1-1) aregreater than or equal to 0; a union of all carrier-group single-subframeresource sets of the carrier set C is the candidate single-subframeresource set S, wherein the carrier-group single-subframe is asingle-subframe resource which includes subchannels located on at leastone carrier of one carrier group.

In some embodiments, the process of the UE selecting at least onesingle-subframe resource in the set S according to any one of:

the UE selecting one carrier-group single-subframe resource for datatransmission in the set S, wherein the UE randomly selects onecarrier-group single-subframe resource with equal probability from theset S; or, the UE randomly selects one carrier group G with equalprobability from all carrier groups of the carrier set C, and randomlyselects one carrier-group single-subframe resource with equalprobability from the set SG;

the UE selecting multiple carrier-group single-subframe resources fordata transmission from the set S, wherein the UE selects at most onecarrier-group single-subframe resource in each carrier group; or, the UErandomly selects at least two carrier groups with equal probability orselects all carrier groups of carrier set C, and randomly selects onecarrier-group single-subframe resource with equal probability in eachselected carrier group.

In some embodiments, before the UE selecting the at least onesingle-subframe resource in the set S, the method further includes: theUE excluding one or more candidate single-subframe resources from theset S according to a PSCCH detected in the channel detecting window andan S-RSSI measured in the channel detection window;

the process of the UE selecting at least one single-subframe resource inthe set S comprises: the UE selecting at least one single-subframeresource in remaining carrier-group single-subframe resources of the setS.

In some embodiments, the process of the UE excluding one or morecandidate single-subframe resources from the set S according the PSCCHdetected in the channel detecting window and the S-RSSI measured in thechannel detecting window includes:

if the UE detects the PSCCH in subframe t_(m) ^(SL) in the channeldetection window on carrier c, c=0, 1, . . . , N1−1, and a value of apriority field in the PSCCH is prio_(RX), according to a resourcereservation indication, the PSCCH reserves the same frequency resourcein subframe t_(m+P) _(rsvp_RX) ^(SL), and the PSSCH-RSRP measured on aPSSCH scheduled by the PSCCH is higher than a threshold Th_(prio) _(TX)_(,prio) _(RX) ^(c), wherein prio_(RX) denotes a value of the priorityfield in a subsequently transmitted PSCCH indicated by a higher layer ofthe UE, Th_(prio) _(TX) _(,prio) _(RX) ^(c) denotes a threshold for thePSSCH-RSRP when the value of the priority field of the subsequentlytransmitted PSCCH indicated by the higher layer of the UE is prio_(TX),whereas the measured priority of the PSCCH is prio_(RX); then:

if carrier c belongs to carrier group G, for any carrier-groupsingle-subframe resource R_(x) _(g) _(,y) ^(G) in subset SG of set S, ifthere is a variable j∈{0, 1, . . . , C_(resel)−1} which makes acarrier-group single-subframe resource

R_(x_(g), y + j × P_(rsvp _ TX))^(G)

overlap with the reserved resource indicated in the PSCCH, whereinCresel denotes the number of times of that the resource is to bereserved after resource reselection of the UE, P_(rsvp_TX) denotes anassumed resource reservation period for determining the availablecandidate single-subframe resource indicated by higher layer of the UE,the UE deleting the single-subframe resource R_(x) _(g) _(,y) ^(G) fromthe set SG;

for any remaining single-subframe resource R_(x) _(g) _(,y) ^(G) insubset SG of the set S, G=0, 1, . . . , R−1, the UE calculating anaverage value of the S-RSSI measured on subchannels x=k′ on carrier giin subframe t_(y-P*j) ^(SL) in the channel detection window, wherein jis an integer larger than 0, i=0, 1, . . . , M1−1 and k′=0, . . . ,L_(subCH) ^(c)−1, p is a predetermined value and denotes an S-RSSIaverage period; the value of the S-RSSI is noted by E_(x,y) ^(G); the UEexcluding 1−X2% resources with highest E_(x,y) ^(G), from the remainingsingle-subframe resources in the set SG, wherein X2 is a predefinedvalue.

In some embodiments, before the UE selecting the at least onesingle-subframe resource in the set S, the method further includes: ifthe UE is to perform a receiving operation in at least one subframeafter subframe n on at least one carrier, the UE excluding one or morecandidate single-subframe resources which overlap or conflict with theat least one subframe from the set S.

In some embodiments, the receiving operation that the UE is to performincludes any one of:

receiving SLSS in subframe m on at least one carrier according to anSLSS receiving rule;

receiving a downlink control or data channel in subframe m on at leastone carrier according to a downlink receiving control behavior or a datachannel receiving behavior, wherein the downlink control or data channelincludes at least one of:

a Physical Downlink Control Channel (PDCCH) indicating a Random AccessResponse (RAR) and a Physical Downlink Shared Channel (PDSCH) carryingthe RAR;

a Physical Broadcast Channel (PBCH);

a PDCCH indicating transmission of broadcast signaling and PDSCHcarrying the broadcast signaling; and

a PDSCH transmitted in a Semi-Persistent Scheduling (SPS) manner.

In some embodiments, the method further includes:

after the UE selects the at least one single-subframe resource,occupying the selected single-subframe resource for Y1 periods followinga predefined resource reservation periodicity in a semi-persistentmanner; when the UE occupies the selected single-subframe resource inthe semi-persistent manner, if the size of data packets transmitted bythe UE changes, and new data packets cannot be born by the currentsingle-subframe resource even if the highest allowable modulation leveland rate are used, the UE giving up the currently selectedsingle-subframe resource, and reselecting a single-subframe resourceaccording to the resource selection or reselection method; or, the UEkeeping the currently selected single-subframe resource, and executingthe resource selection or reselection method to select an additionalsingle-subframe resource on a carrier other than that where the currentsingle-subframe resource is located.

In some embodiments, before transmitting the PSSCH, the method furtherincludes:

if the UE is to transmit signals on multiple carriers simultaneously,and the number of carriers on which the UE needs to perform transmissionsimultaneously is greater than the number of current available radiotransmission chains of the UE, the UE prioritizing transmission ofsignals with a high priority and giving up transmission of signals witha low priority;

if the UE is to transmit signals simultaneously on two or more carriers,and the UE does support simultaneous transmission on multiple carriers,the UE prioritizing transmission of signals with a high priority andgiving up transmission of signals with a low priority;

if the UE is to transmit signals on at least two carrierssimultaneously, the UE adjusting a transmit power, wherein the signalsinclude at least one of PSSCH, PSCCH and uplink signals;

the UE adjusting the transmit power according to the following:

process 1, if the value of a priority field of the PSCCH transmitted bythe UE on at least one carrier is greater than or equal tothresSL-TxPrioritization, wherein thresSL-TxPrioritization denotes aspecific priority threshold, the UE adjusting a sidelink transmit poweron one or more carriers whose priority field has the value greater thanor equal to thresSL-TxPrioritization, so as to make a total transmitpower of the UE lower than an allowable maximum transmit power PCMAX ofthe UE;

process 2, if values of priority fields of the PSCCH on all currentsidelink carriers of the UE are lower than thresSL-TxPrioritization, orthe total transmit power is still higher than PCMAX after the UE adjuststhe transmit power on all carriers meeting the condition in process 1 to0, and the UE transmits uplink signals on at least one carrier, the UEadjusting the transmit power of the uplink signals on the at least onecarrier, so as to make the total transmit power of the UE lower than theallowed maximum transmit power PCMAX of the UE;

process 3, if the values of the priority fields of the PSCCH on allcurrent sidelink carriers of the UE are lower thanthresSL-TxPrioritization, and the UE does not transmit uplink signal onany carrier, the UE adjusting the sidelink signal transmit power on thecarriers, so as to make the total transmit power of the UE lower thanthe allowed maximum transmit power PCMAX of the UE;

or, the UE adjusting the transmit power according to the following:

the UE determining a priority of the transmission signal on eachcarrier, adjusting the transmit power of at least one carrier fortransmitting data with lowest priority, so as to make the total transmitpower of the UE lower than the allowed maximum transmit power PCMAX ofthe UE; if the total transmit power of the UE is still higher than PCMAXafter the transmit power of the at least one carrier with the lowestpriority is adjusted to 0, the UE repeating the above operations forremaining carriers until the total transmit power of the UE is lowerthan the allowed maximum transmit power PCMAX of the UE;

wherein the priority of the sidelink signal is determined by the valueof the priority field in the PSCCH of the sidelink signal; the higherthe value of the priority field, the lower the priority level; if thereare uplink signals, the priority of the uplink signals is higher thanthe sidelink signal with priority value thresSL-TxPrioritization, butlower than the sidelink signal with priority valuethresSL-TxPrioritization-1, thresSL-TxPrioritization denotes a specificpriority threshold.

Embodiments of the present disclosure also provide a User Equipment (UE)for resource selection or reselection in a Vehicle toVehicle/Pedestrian/Infrastructure/Network or Vehicle to Everything (V2X)communication, including: a candidate time-frequency resourcedetermining module, a resource selection or reselection module and atransmitting module; wherein

the candidate time-frequency resource determining module is to determineat least one carrier on which the UE performs channel detection, and todetermine a candidate single-subframe resource set;

the resource selection or reselection module is to select one or moresingle-subframe resources for data transmission from the candidatesingle-subframe resource set; and

the transmitting module is to transmit PSSCH on the selected one or moresingle-subframe resources.

According to the above method and apparatus, the UE firstly determines acarrier set C available for resource selection or reselection and acandidate single-subframe resource set S in the carrier set C. Then, theUE excludes some candidate single-subframe resources from the set Saccording to a channel detection result. Finally, the UE selects one ormore single-subframes from the remaining single-subframe resources of ehset S for PSSCH transmission. Through the technical solution provided bythe present disclosure, the probability of selecting the frequencyresources in the same subframe is increased when the UE performsresource selection or reselection on multiple carriers, whicheffectively overcomes the half-duplex restriction and IBE interferenceexisting in the multi-carrier sidelink communication scenario, andimproves the performance of the V2X system.

BRIEF DESCRIPTION OF THE DRAWINGS

The above said and/or additional aspects and advantages will becomeobvious and be easily understood from the following description of theembodiments in combination with the accompanying drawings, wherein:

FIG. 1 is a flow chart of a resource selection or reselection methodaccording to an embodiment of the present disclosure; and

FIG. 2 is a block diagram of user equipment (UE) which performs aresource selection or reselection method in V2X communication accordingto an embodiment of the present disclosure.

FIG. 3 is a flowchart illustrating a resource allocation according tosome embodiments of the present disclosure.

FIG. 4 is a schematic diagram illustrating a resource pattern accordingto some embodiments of the present disclosure.

FIG. 5 is a schematic diagram illustrating a single-slot resourceconsisting of RBGs according to some embodiments of the presentdisclosure.

FIG. 6 is a schematic diagram illustrating single-slot resourcesconsisting of PRBs with specified indexes in RBGs according to someembodiments of the present disclosure.

FIG. 7 is a schematic diagram illustrating a candidate resource patternin a specific resource selection window according to some embodiments ofthe present disclosure.

FIG. 8 is a block diagram illustrating a structure of an apparatus forresource allocation according to various embodiments of the presentdisclosure.

FIG. 9 is a flowchart illustrating a resource selection or reselectionmethod according to some embodiments of the present disclosure.

FIG. 10 is a schematic diagram illustrating carrier groupsingle-subframe resource according to some embodiments of the presentdisclosure.

FIG. 11 is a block diagram illustrating a structure of a UE forperforming the resource selection or reselection in the V2Xcommunication according to various embodiments of the presentdisclosure.

DETAILED DESCRIPTION

The embodiments of the present disclosure will be described in detailbelow. Examples of said embodiments are shown in the accompanyingdrawings, and the same or similar reference represents the same orsimilar element or elements with same or similar functions throughoutthe disclosure. In the following, the described embodiments referring tothe accompanying drawings are exemplary and only used to illustrate thepresent disclosure, but not intend to be interpreted as the limit of thepresent disclosure.

Those skilled in the art may understand that unless statedintentionally, the singular forms “a”, “an”, “said” and “the” usedherein may also comprise plural forms. It should also be furtherunderstood that the wording “comprise” used in the specification of thepresent disclosure refers to the existence of the feature, integer,step, operation, element and/or component, but does not exclude theexistence or adding of one or more other features, integers, steps,operations, elements, components and/or combinations thereof. It shouldbe understood that when we say that an element is “connected” or“coupled” to another element, it can be directly connected or coupled toanother element, or there may also be an intermediate element. Inaddition, the “connection” or “coupling” used herein may comprisewireless connection or wireless coupling. The wording “and/or” usedherein comprises all or any unit and all combinations of one or moreassociated listed items.

Those skilled in the art may understand that unless defined otherwise,all the terms used herein (comprising technical terms and scientificterms) have the same meanings as generally understood by those ofordinary skills in the art of the present disclosure. It should also beunderstood that those terms defined in general dictionaries should beunderstood to have meanings consistent with those in the context of theprior art, and unless specially defined like here, those terms will notbe construed by ideal or excessively formal meanings.

Those skilled in the art may understand that the “user equipment” and“terminal device” used herein comprise both a device of a wirelesssignal receiver, which is a device only having a wireless signalreceiver with no transmitting capability, and a device comprisingreceiving and transmitting hardware, which is a device having receivingand transmitting hardware that is able to perform bidirectionalcommunication on a bidirectional communication link. Such device maycomprise: cellular or other communication devices, which have a singlecircuit display or a multi-circuit display, or cellular or othercommunication devices without a multi-circuit display; a PCS (PersonalCommunications Service), which may combine voice, data processing, faxand/or data communication capabilities; a PDA (Personal DigitalAssistant), which may comprise a radio frequency receiver, pager,Internet/Intranet access, network browser, notepad, calendar and/or GPS(Global Positioning System) receiver; and a conventional laptop and/orpalmtop computer or other devices, which have a conventional laptopand/or palmtop computer or other devices comprising a radio frequencyreceiver. The “user equipment” and “terminal device” used herein may beportable, transportable and mounted in means of transportation (air,maritime and/or land), or appropriate and/or configured to run locally,and/or to run on earth and/or run at any other position in space in adistributed form. The “user equipment” and “terminal device” used hereinmay further be a communication terminal, Internet access terminal,music/video playing terminal, for example, may be a PDA, MID (MobileInternet Device) and/or mobile phone having a music/video playingfunction, and may also be a smart television, set top box, and the like.

In order to increase resource utilization efficiency and improve V2Xsystem performance at the same time, it is necessary for UEs which useMode 3 and UEs which use Mode 4 to work in the same resource pool. Inthis case, in order to avoid or reduce mutual interference between thetwo kinds of UE, the present application proposes a resource selectionand reselection method in V2X communication.

FIG. 1 is a flow chart of a resource selection or reselection methodaccording to an embodiment of the present disclosure.

Referring to FIG. 1, in step 101, a UE detects physical sidelink controlchannel (PSCCH) in a format of Sidelink Control Information (SCI) xtransmitted by other UEs. For example, the UEs are UEs using Mode 4. TheUE detects the PSCCH transmitted by other UEs to obtain at least one ofthe following information: a transmission mode used by the UE whichtransmits the PSCCH, a priority of PSSCH scheduled by the PSCCH,frequency domain resource position of PSSCH scheduled by the PSCCH, aresource reservation period indicated by the PSCCH and the like.

The UE may detect SCI x on all PSCCH resources in a transmissionresource pool currently selected by the UE, or only detect SCI x on somePSCCH resources in the transmission resource pool currently selected bythe UE, for example, the UE determines positions of the some PSCCHresources by receiving signalling of an eNB. For example, the UE onlydetects SCI x on the last PSCCH resource on the frequency domain in eachsubframe in the transmission resource pool currently selected by the UE,or only detects SCI x on the last PSCCH resource on the frequency domainin some subframes in the transmission resource pool currently selectedby the UE.

In step 102, the UE selects a single-subframe resource fromsingle-subframe resources which do not overlap with single-subframeresources reserved by the detected PSCCH.

Defining a single-subframe resource, R_(x,y) is L_(subCH) continuoussubchannels starting from subchannel x on TTI t_(y) ^(SL), wherein yrepresents a relative index of the TTI t_(y) ^(SL) in the resource pool,and L_(subCH) is determined by high layers of UE, and represents thenumber of subchannels used for PSSCH transmission. If the UE performsresource selection or reselection on subframe n, then the UE shouldconsider L_(subCH) continuous subchannels on any one of subframesbelonging to the resource pool within a range [n+T₁,n+T₂] as candidatesingle-subframe resources, wherein T1 and T2 are determined by the UEembodiment, and T1≤4, 20≤T2≤100, denoting the total number ofsingle-subframe resources as Mtotal, and a set composed of Mtotalcandidate subframe resources as S. It should be specially noted that ifthe UE uses multiple TTI lengths in the resource pool, for example, someUEs use TTI of 1 ms length, and some other UEs use TTI of 0.5 ms length,the UE may consider that TTI length of single-subframe resource is thesame as TTI length used by the UE when performing resource selection orreselection.

For any one single-subframe resource R_(x,y) in the set S, if there is avariable j∈{0, 1, . . . , C_(resel)−1} that makes a single-subframeresource

R_(x, y + j × P_(rsvp _ TX))

overlap with a reserved resource indicated by the SCI x, wherein Creselrepresents the number of times that resources are planned to be reservedafter UE resource reselection, and P_(rsvp_TX) represents a resourcereservation interval assumed when determining available candidatesingle-subframe resources which is indicated by UE high layer, then theUE excludes the single-subframe resource R_(x,y) when selecting orreselecting resources.

According to one embodiment of the present disclosure, if the detectedSCI x is in a particular format, then a single-subframe resource isselected from single-subframe resources which do not overlap withsingle-subframe resources reserved by the detected PSCCH.

According to another embodiment of the present disclosure, if thedetected SCI x is in a particular format, and value of the filedpriority, prio_(RX), contained in the SCI x is greater than a certainvalue, then a single-subframe resource is selected from single-subframeresources which do not overlap with single-subframe resources reservedby the detected PSCCH.

For example, the particular PSCCH format is SCI 1 defined in 3GPPrelease 14, or a format different from the SCI 1 defined in 3GPP release14, or a format which contains the same number of bits as SCI 1,meanings of fields in which are the same with those in SCI 1 defined in3GPP release 14, and one or more particular bits in reserved bits filedare 1.

According to yet another embodiment of the present disclosure, the UEfurther measures a sidelink reference signal received power of a PSSCH(PSSCH-RSRP) scheduled by SCI x. If the PSSCH-RSRP is higher than aparticular threshold, then a single-subframe resource is selected fromsingle-subframe resources which do not overlap with single-subframeresources reserved by the detected PSCCH. Specifically, value ofpriority filed contained in SCI x is prio_(RX), a single-subframeresource where a PSSCH scheduled by the SCIx is R_(sr,m), and value ofPSSCH-RSRP measured by the UE on the single-subframe resource R_(xr,m)is greater than Th_(prio) _(TX) _(+Δ,prio) _(RX) wherein prio_(TX)represents value of a priority filed of a PSCCH to be transmitted nextwhich is indicated by UE higher layer, Δ is a value configured orpreconfigured by the eNB, and Th_(prio) _(TX) _(+Δ,prio) _(RX)represents an ith SL-ThresPSSCH-RSRP in SL-ThresPSSCH-RSRP-List-r14defined in 3GPP standard 36.331 V14.1.0, whereini=(prio_(TX)+Δ)*8+prio_(RX)+1, then the UE excludes the single-subframeresource Rx,y from S when selecting or reselecting resources.

The UE further excludes resources in the set S in a manner defined in3GPP release 14.

In step 103, the UE transmits a physical sidelink shared channel (PSSCH)on selected single-subframe resources.

The above technical solution of the present application will be furtherdescribed in interaction between devices, combined with specificapplication cases below.

Case I

In case I, the SCI x is type I, and type I may be a new PSCCH formatdifferent from existing SCI 1 (i.e. SCI 1 defined in 3GPP release 14),or type I has the same number of bits as the existing SCI 1, and themeanings of various fields are the same, but one or more particular bitsin reserved bits field may be 1 (all bits in reserved bits field ofexisting SCI 1 are 0). A UE selects single-subframe resources fromsingle-subframe resources which do not overlap with single-subframeresources reserved by detected PSCCH when performing resource selectionor reselection. The specific steps are as follows:

in step 201, a UE detects SCI x transmitted by other UE(s).

For example, in this case, UEs transmitting the SCI x are UEs using Mode3.

According to one implementation of this case, a UE using Mode 3determines values of various fields in the SCI x by receiving physicallayer control signalling of an eNB. The physical layer signalling shouldat least contain a value of a “number of subframes in a resource poolcorresponding to a resource reservation interval” field in the SCI xindicated, and a value of “number of subchannels and positions ofcontained subchannels” field in the SCI x. Preferably, the physicallayer signalling is UE-specific signalling, scrambled by a particularcell radio network temporary identifier (C-RNTI), and choosing which UEas a transmitting UE of the SCI x is determined by the eNBimplementation. According to another implementation of this case, a UEusing Mode 3 determines values of various fields in the SCI x byreceiving physical layer control signalling and higher layer signallingof an eNB. The physical layer signalling should at least contain a valueof a “number of subframes in a resource pool corresponding to a resourcereservation interval” field in the SCI x indicated, and the higher layersignalling should contain a value of a “number of subframes in aresource pool corresponding to a resource reservation interval” field inthe SCI x indicated. The physical layer control signalling in the abovetwo implementations should be distinguished from the downlink controlindication format 5A (DCI 5A) defined in a current standard. The UEwhich receives the physical layer control signalling only transmits SCIx according to the indication, but does not transmit PSSCH on indicatedfrequency resources.

According to implementation I of this case, SCI x differs from theexisting SCI 1, and the content of the SCI x should contain one or moreitems of the following information: priority information, the number ofsubframes in a resource pool corresponding to a resource reservationinterval D1, CRC, a subframe gap of a first reserved resource G1, andthe number and positions of subchannels contained in single-subframeresources, wherein a subframe position of the first reserved resourcemeans a gap between a subframe where the SCI x is located and a subframewhere the first reserved resource is located. If the subframe where theSCI x is located is m, then in this case, the UE considers thatresources indicated by a “number of subchannels and positions ofcontained subchannels” field on subframe m+j x G1+i x D1 have beenreserved, wherein i=0, 1, 2, . . . , M′−1, the value of M′ is defined bystandard or configured by the eNB, and M′ can be positive infinity; andj=0 and/or 1, the specific value is defined by a standard or configuredby the eNB. It needs to be specially noted that if D1 in the SCI x isindicated as a particular value, e.g. 0, or the SCI x does not contain“the number of subframes in a resource pool corresponding to a resourcereservation interval D1”, then the UE may replace D1 in the formula m+jx G1+i x D1 with Pstep or Pmin, wherein Pstep is a basic resourcereservation interval of a current resource pool, while Pmin is a minimumresource reservation interval supported by the current resource pool. UEdetermines specific values of these two parameters by receiving eNBsignalling, standard definition or preconfiguration.

According to implementation II of this case, fields and the number ofbits of each field contained in the SCI x and the existing SCI 1 are thesame, while a certain or certain particular bit(s) in seven bits inreserved bits field are 1, for example, the first bit in the reservedbits field is 1, in order to distinguish SCI x from SCI 1. If thesubframe where the SCI x is located is m, then in this case, the UEconsiders that resources indicated by a “positions of frequencyresources and the number of contained subchannels” field on subframe m+jx G2+i x D2 are reserved, wherein i=0, 1, 2, . . . , M′-1, the value ofM′ is defined by a standard or configured by the eNB, and M′ can bepositive infinity; j=0 and/or 1, the specific value is defined by astandard or configured by the eNB; and G2 is a value of a time gapbetween initial transmission and retransmission in the SCI 1, and D2 isthe number of subframes corresponding to a value of a resourcereservation interval field in the SCI 1.

In step 202, with regard to any one single-subframe resource R_(x,y) inthe set S, if there is a variable j∈{0, 1, . . . , C_(resel)−1} thatmakes a single-subframe resource R_(x,y+j×P) _(rsvp_TX) overlap with areserved resource indicated by the SCI x, wherein Cresel represents thenumber of times that resources are planned to be reserved after UEresource reselection, and P_(rsvp_TX) represents a resource reservationinterval assumed when determining available candidate single-subframeresources which is indicated by the UE high layer, then the UE excludesthe single-subframe resource Rx,y from S when selecting or reselectingresources. Or, if a value prio_(RX) of a priority field (Priority)contained in the SCI x is greater than a particular value, then the UEexcludes the single-subframe resource R_(x,y) from S in resourceselection or reselection.

The UE may further exclude resources in the set S in a manner defined in3GPP release 14.

The UE randomly selects one single-subframe resource from the remainingresources for data transmission.

In step 203, the UE transmits the PSCCH on a PSCCH resourcecorresponding to the selected single-subframe resource, and transmitsthe PSSCH on the selected single-subframe resource.

Case II

In case II, the SCI x may be type II or type III, wherein type II is thesame as the existing SCI 1 (i.e. SCI 1 defined in 3GPP release 14), andpreferably, a transmitting UE of type II is a Rel-14 UE working in Mode3. Type III is different from the SCI 1, for example, the value(s) ofone or more particular bits in reserved bits field is(are) 1.Preferably, a transmitting UE of type III is a new release UE working inMode 4. According to implementation I of this case, if the datatransmitted by a new release UE working in Mode 3 needs to be receivedby a legacy UE, the new release UE of Mode 3 transmits SCI type II.According to implementation II of this case, if the data transmitted bya new release UE working in Mode 3 needs to be received by a legacy UE,the new release UE of Mode 3 transmits SCI type III. At the same time,SCI x type I, type II and type III are different from each other. If theSCI x received by the UE is type II, then after the UE receives the SCIx, the UE may further measure PSSCH-RSRP of a PSSCH scheduled by the SCIx. When the UE performs resource selection or reselection, with regardto any one single-subframe resource in candidate single-subframeresource set S, if it may overlap with a single-subframe resourcereserved by the UE transmitting SCI x, then the UE should directlyexclude it; or, if it may overlap with a single-subframe resourcereserved by the UE transmitting SCI x, and the measured PSSCH-RSRP isgreater than a certain particular threshold, then the UE should excludethe single-subframe resource; and preferably, the value of theparticular threshold should be higher than Th_(prio) _(TX) _(,prio)_(RX) wherein prio_(RX) is a value of a priority field contained in theSCI x, prio_(TX) represents a value of a priority field of PSCCH to betransmitted next indicated by a UE high layer, and Th_(prio) _(TX)_(,prio) _(RX) represents an ith SL-ThresPSSCH-RSRP inSL-ThresPSSCH-RSRP-List-r14 defined in 3GPP standard 36.331 V14.1.0,i=prio_(TX)*8+prio_(RX)+1. If the SCI x received by the UE is type III,then after receiving the SCI x, the UE further measures PSSCH-RSRP of ascheduled PSSCH, and when the UE performs resource selection orreselection, with regard to any one single-subframe resource incandidate single-subframe resource set S, if the single-subframeresource may overlap with a single-subframe resource reserved in the SCIx, and the measured PSSCH-RSRP is greater than a certain particularthreshold, then the UE should exclude the single-subframe resource.Preferably, only when the UE works in a particular resource poolconfigured by an eNB, the following operations will be performed, forexample, the particular resource pool is a transmitting resource poolconfigured for a 3GPP release 14 Mode 3 UE. The steps are as follows:

in step 301, a UE detects SCI x transmitted by other UE(s).

In this case, if the SCI x received by the UE at subframe M′ iscompletely the same as the existing SCI 1, the UE can determine reservedresource in the following two ways:

Way 1: the UE considers that resources indicated by a “positions offrequency resources and the number of contained subchannels” field onsubframe m+j x G3+i x D3, are reserved, wherein i=0, 1, 2, . . . , M′−1,the value of M′ is defined by a standard or configured by the eNB, andM′ can be positive infinity. It should be specially noted that the valueof M′ can be related to value of D3_(l). For example, when D3_(l) is100, M′ is 1. If D3_(l) is p and p is smaller than 100, M′ is equal to100/p. j=0 and/or 1, the specific value is defined by a standard orconfigured by the eNB; and G3 is a value of a time gap between initialtransmission and retransmission in the SCI 1, and D3 is the number ofsubframes corresponding to a value of a resource reservation intervalfield in the SCI 1. l=0, 1, . . . N′−1,and value of individual elementin the set {D30, D31, D32, . . . , D3N−1} is indicated via RRC layersignaling or physical layer signaling by eNB. If it is implementation Iof this case, the set can represent number of subframes corresponding toSPS period used by the Rel-14 UE working in Mode 3 in the currentresource pool. If it is implementation II of this case, the set canrepresent number of subframes corresponding to SPS period(s) used by theRel-14 UE working in Mode 3, and number of subframes corresponding toSPS period(s) used by the new release UE working in Mode 3 andtransmitting the date that needs to be received by a legacy UE.

Way 2: If the number of subframes corresponding to the value of Resourcereservation interval field in SCI x is zero, UE determines reservedresource in Way 1; If the number of subframes corresponding to the valueof Resource reservation interval field in SCI x is more than zero, it isconsidered that the resource(s) indicated by the “positions of frequencyresources and the number of contained subchannels” field in subframem+j×G3+i×D3 is/are reserved, wherein i=0, 1, 2, . . . , M′−1, the valueof M′ is defined by a standard or configured by the eNB, and M′ can bepositive infinity. It should be specially noted that the value of M′ canbe related to value of D3. For example, when D3 is 100, M′ is 1. If D3is p and p is smaller than 100, M′ is equal to 100/p. j=0 and/or 1, thespecific value is defined by a standard or configured by the eNB; and G3is a value of a time gap between initial transmission and retransmissionin the SCI 1, and D3 is the number of subframes corresponding to a valueof a resource reservation interval field in the SCI x.

If the SCI x received by the UE at a subframe M′ is not completely thesame as the existing SCI 1, for example, fields contained in the SCI xand the number of bits of each field are the same as those of the SCI 1but a certain or certain particular bit(s) in reserved bits field are 1,the UE considers that resources indicated by a “positions of frequencyresources and the number of contained subchannels” field on subframe m+jx G4+D4 are reserved, j=0 and/or 1, and the specific value is defined bya standard or configured by the eNB; and G4 is a value of a time gapbetween initial transmission and retransmission in the SCI x, and D4 isthe number of subframes corresponding to a value of a resourcereservation interval field in the SCI x.

In step 302, if the SCI x is type II, with regard to any onesingle-subframe resource R_(x,y) in the set S, if there is a variablej∈{0, 1, . . . , C_(resel)−1} that makes a single-subframe resource

R_(x, y + j × P_(rsvp _ TX))

overlap with a reserved resource indicated by the SCI x, wherein Creselrepresents the number of times that resources are planned to be reservedafter UE resource selection or reselection, and P_(rsvp_TX) represents aresource reservation interval assumed when determining availablecandidate single-subframe resources which is indicated by the UE highlayer, then the UE excludes the single-subframe resource R_(x,y) from Swhen selecting or reselecting resources. Or, with regard to any onesingle-subframe resource R_(x,y) in the set S, there is a variable j∈{0,1, . . . , C_(resel)−1} that makes a single-subframe resourceR_(x,y+j×P) _(rsvp_TX) overlap with a reserved resource indicated by theSCI x, wherein Cresel overlap with a reserved resource indicated by theSCI x, wherein P_(rsvp_TX) represents a resource reservation intervalassumed when determining available candidate single-subframe resourceswhich is indicated by the UE high layer. If a value prio_(RX) of apriority field contained in the SCI x is greater than a particularvalue, then the UE excludes the single-subframe resource R_(x,y) from Swhen selecting or reselecting resources. Or, with regard to any onesingle-subframe resource R_(x,y) in the set S, there is a variable j∈{0,1, . . . , C_(rexel)−1} in the set S, there is a variable R_(x,y+j×P)_(rsvp_TX) overlap with a reserved resource indicated by the SCI x,wherein Cresel represents the number of times that resources are plannedto be reserved after UE resource selection or reselection, andP_(rsvp_TX) represents a resource reservation interval assumed whendetermining available candidate single-subframe resources which isindicated by UE high layer. If the UE measures PSSCH-RSRP of a PSSCHscheduled by the SCI x, and the value of the measured PSSCH-RSRP isgreater than Th_(prio) _(TX) _(+Δ,prio) _(RX) or Th_(prio) _(TX)_(,prio) _(RX) _(+Δ), wherein prio_(TX) represents a value of a priorityfield of a PSCCH to be transmitted next indicated by UE high layer, Δ isa value configured or preconfigured by the eNB, and Thab represents anith SL-ThresPSSCH-RSRP in SL-ThresPSSCH-RSRP-List-r14 defined in 3GPPstandard 36.331 V14.1.0, wherein i=a*8+b+1, then the UE excludes thesingle-subframe resource R_(x,y) from S in resource selection orreselection.

In this case, if the SCI x is type III, then the UE should measurePSSCH-RSRP of a PSSCH scheduled by the SCI x, with regard to any onesingle-subframe resource R_(x,y) in the set S, there is a variable j∈{0,1 . . . , C_(resel)−1} that makes a single-subframe resource R_(x,y+j×P)_(rsvp_TX) overlap with a reserved resource indicated by the SCI x,wherein Cresel represents the number of times that resources are plannedto be reserved after UE resource selection or reselection, andP_(rsvp_TX) represents a resource reservation interval assumed whendetermining available candidate single-subframe resources which isindicated by UE high layer, if the value of the measured PSSCH-RSRP isgreater than Th_(prio) _(TX) _(,prio) _(RX) , wherein prio_(TX)represents a value of a priority field of a PSCCH to be transmitted nextindicated by the UE high layer, and Th_(prio) _(TX) _(,prio) _(RX)represents an ith SL-ThresPSSCH-RSRP in SL-ThresPSSCH-RSRP-List-r14defined in 3GPP standard 36.331 V14.1.0, whereini=prio_(TX)*8+prio_(RX)+1, then the UE excludes the single-subframeresource R_(x,y) from S in resource selection or reselection.

The UE may further exclude resources in the set S in a manner defined in3GPP release 14.

The UE randomly selects one single-subframe resource from the remainingresources for data transmission.

In step 303, the UE transmits the PSCCH on a PSCCH resourcecorresponding to the selected single-subframe resources, and transmitsthe PSSCH on the selected single-subframe resource.

When transmitting PSCCH, UE working in Mode 3 can set the value ofPriority field in PSCCH to a value lower than the priority indicated byhigh layer. Specifically, if the priority indicated by high layer is pr,the value of Priority field in PSCCH transmitted by UE can be set topr-Δ, wherein Δ is a particular value, configured by eNB, defined instandard or preconfigured. In this way, UE working in Mode 3 can bebetter protected.

Case III

In case III, the SCI x may be type I, type II or type III. If the SCI xreceived by the UE is type I or type II, then after the UE receives theSCI x, the UE may further measure PSSCH-RSRP of a PSSCH scheduled by theSCI x, and when the UE performs resource selection or reselection, withregard to any one single-subframe resource in a candidatesingle-subframe resource set S, if it overlaps with a single-subframeresource reserved in the SCI x, then the UE should directly exclude it;or, if it overlaps with a single-subframe resource reserved in the SCIx, and the measured PSSCH-RSRP is greater than a certain particularthreshold, then the UE should exclude the single-subframe resource. Ifthe SCI x received by the UE is type III, then after receiving the SCIx, the UE further measures PSSCH-RSRP of a scheduled PSSCH, and when theUE performs resource selection or reselection, with regard to any onesingle-subframe resource in a candidate single-subframe resource set S,if the single-subframe resource overlaps with a single-subframe resourcereserved in the SCI x, and the measured PSSCH-RSRP is greater than acertain particular threshold, then the UE should exclude thesingle-subframe resource. The steps are as follows:

in step 401, a UE detects SCI x.

In this case, if the SCI x received by the UE at a subframe m is type I,then a method for the UE to determine reserved resources is the same ascase I, which will not be described herein anymore. If the SCI xreceived by the UE at subframe m is type II or type III, then a methodfor the UE to determine reserved resources is the same as case II, whichwill not be described herein anymore.

In step 402, if the SCI x is type I, then the UE should excludesingle-subframe resources which overlap with reserved resources of theSCI x from the set S according to the method in embodiment I; and if theSCI x is type II or type III, then the UE should exclude single-subframeresources which overlap with reserved resources of the SCI x from theset S according to the method in embodiment II. These will both not bedescribed herein. The UE may further exclude resources in the set S in amanner defined in 3GPP release 14.

The UE randomly selects one single-subframe resource from the remainingresources for data transmission.

In step 403, the UE transmits the PSCCH on a PSCCH resourcecorresponding to the selected single-subframe resource, and transmitsthe PSSCH on the selected single-subframe resource.

Case IV

In case IV, a UE works in Mode 3, and SCI x is type II. When the UEreceives that resources allocated by eNB signalling have changed, forexample, a data generation period or subframe offset indicated by theSCI x has changed, the UE at least performs channel detection onresources or some resources indicated by the eNB, and selects orreselects resources according to a detection result. The steps are asfollows:

The UE starts performing channel detection after receiving a sidelinkresource allocation indication (i.e. DCI 5A) transmitted by the eNB.

According to implementation I of this case, if a single-subframeresource allocated by the eNB is R_(x,y), then the UE should detectsingle-subframe resource R_(x,y+j×P) _(step) , wherein Pstep representsa basic resource reservation period in a current resource pool, j=1, 2,3, . . . I1, the value of I1 is defined by a standard, configured orpreconfigured by the eNB, representing a maximum detection period, e.g.I1=10 or 1, or 5.

According to implementation II of this case, if a single-subframeresource allocated by the eNB is R_(x,y) then the UE should detectsingle-subframe resource

R_(x, y + j × P_(rsvp _ TX)),

wherein j=1, 2, 3, . . . I2, the value of I2 is defined by a standard,configured or preconfigured by the eNB, representing a maximum detectionperiod, e.g. I2=10, or 1, or 5, wherein Prsvp_TX is a current resourcereservation period of the UE, and this value is indicated by the eNB.

According to implementation III of this case, if a single-subframeresource allocated by the eNB is R_(x,y), then the UE should detectsingle-subframe resource R_(x,y+j×Pm), wherein j=1, 2, 3, . . . I3, thevalue of I3 is defined by a standard, configured or preconfigured by theeNB, representing a maximum detection period, e.g. I2=10, or 1, or 5;and Pm is a minimum resource reservation period supported in the currentresource pool.

According to implementation IV of this case, if a single-subframeresource allocated by the eNB is R_(x,y), then the UE should detectsubframe y. The UE receives the SCI x at subframe y and resourcesscheduled or reserved by the SCI x overlap with

R_(x, y + j × P_(rsvp _ TX)),

j=1, 2, 3, . . . , and PSSCH-RSRP of the resources scheduled by the SCIx exceed a threshold, then the resource

R_(x, y + j × P_(rsvp _ TX))

are unavailable. Or, the UE may also determine whether the resource

R_(x, y + j × P_(rsvp _ TX))

is available by measuring S-RSSI based on subframe y and comparing thesame with a particular threshold. The above particular threshold isdefined by a standard, configured or preconfigured by the eNB, whereinPrsvp_TX is a current resource reservation period of the UE, andindicated by the eNB.

According to implementation V of this embodiment, if a single-subframeresource allocated by the eNB is R_(x,y), then the UE should detect asubframe before subframe y+I₄×P_(rsvp_TX), the value of I4 defined by astandard, configured or preconfigured by the eNB, representing a maximumdetection period, e.g. I4=10, or 1, or 5, so as to determine whetherresource

R_(x, y + I₄ × P_(rsvp_TX) + j × P_(rsvp_TX)),

j=0, 1, 2, . . . is available. If the SCI x is received and resourcesscheduled or reserved by the SCI x overlap with

R_(x, y + I₄ × P_(rsvp_TX) + j × P_(rsvp_TX)),

and PSSCH-RSRP of the resource scheduled by the SCI x exceeds athreshold, then the resource

R_(x, y + I₄ × P_(rsvp_TX) + j × P_(rsvp_TX))

is unavailable. Or, the UE may also determine whether the resource

R_(x, y + I₄ × P_(rsvp_TX) + j × P_(rsvp_TX))

is available by measuring S-RSSI based on that before subframey+I₄×P_(rsvp_TX) and comparing the same with a particular threshold. Forexample, with regard to P_(rsvp_TX)=k×P_(step), k=1, ½, ⅕, S-RSSI is anaverage value of S-RRSIs measured on resource

R_(x, y + k × P_(rsvp _ TX)),

j=0, 1,

I4-1; and with regard to P_(rsvp_TX)=k×P_(step) k>1, S-RSSI is anaverage value of S-RRSIs measured on the resource R_(x,y+k×P) _(step) ,j=0, 1, . . . (I₄×P_(rsvp_TX))/P_(step)−1. The above particularthreshold is defined by a standard, configured or preconfigured by theeNB, wherein Prsvp_TX is a current resource reservation period of theUE, and this value is indicated by the eNB.

According to implementation VI of this embodiment, when a UE anticipatesthat a base station is to change a period of a configured SPS resourceor a subframe offset, the UE starts performing a detection operation.For example, the UE transmits information about a service change to thebase station, for example, a period change, or a change of subframeoffset generated within the period, etc.; or the base station transmitsindication information to the UE, notifying the UE that the period ofthe SPS resource or subframe offset is to be changed. After the UEreceives SCI x of the base station, assuming that single-subframeresource allocated by an eNB is R_(x,y), the UE detects a subframebefore a subframe y and determines whether resource

R_(x, y + j × P_(rsvp _ TX)),

j=1, 2, . . . is available. With regard to any one value of j in theabove value range of j, f the SCI x is received and resources scheduledor reserved by the SCI x overlap with

R_(x, y + j × P_(rsvp _ TX)),

and PSSCH-RSRP of the resources scheduled by the SCI x exceeds athreshold, then the resource

R_(x, y + j × P_(rsvp _ TX))

is available by measuring S-RSSI based on that before subframe ycomparing the same with a particular threshold. For example, with regardto P_(rsvp_TX)=k×P_(step), k=1, ½, ⅕, S-RSSI is an average value ofS-RRSIs measured on the resource R_(x,y−k×P) _(step) , j=0, 1, . . . ;and with regard to P_(rsvp_TX)=k×P_(step), k>1, S-RSSI is an averagevalue of S-RRSIs measured on the resource R_(x,y−k×P) _(step) , j=0, 1,. . . . The above particular threshold is defined by a standard,configured or preconfigured by the eNB, wherein Prsvp_TX is a currentresource reservation period of the UE, and this value is indicated bythe eNB.

In order to support the above operations, the UE should continuouslyperform channel detection on all resources of each subframe in acurrently selected transmitting resource pool, or start performingchannel detection when a UE data generation period changes, and reportthe channel detection result to the eNB. Preferably, if the subframe nsatisfies at least one of the following conditions, the UE reports thechannel detection result to the eNB in subframe n:

Condition 1: The UE satisfies bypass Buffer Status Report (BSR)condition in subframe n, and the service corresponding to the bypass BSRis a V2X service that the UE intends to send in the current resourcepool.

Condition 2: the subframe n satisfies the channel detection resultreporting configuration indicated by the eNB, that is, (n-Δ) mod P=0,where Δ is the channel detection result reporting subframe offsetindicated by the eNB, P is the channel detection result reportingperiod, the UE determines the value of P according to the eNBindication, pre-configuration or standard definition.

Condition 3: subframe n is the first subframe in which there is uplinkscheduling resource for UE after subframe x, where subframe x is thelatest subframe in which the UE receives an indication of channeldetection result reporting of the eNB. The indication of channeldetection result reporting of the eNB may be RRC layer signaling, MAClayer signaling or physical layer signaling.

Preferably, the channel detection result reported by the UE shouldinclude channel conditions on part or all of the subchannels in thesubframe range [n+a, n+b], and for any one of the reported subchannels,its channel conditions include at least one item of the followinginformation: average S-RSSI on the sub-channel, PSSCH-RSRP on thesub-channel, the priority of PSSCH sent by the UE that reserves thesub-channel, the resource reservation period of the UE that reserves thesub-channel, and the like. For example, if UE reporting the channeldetection result is triggered by the condition 1, the values of a and bare determined by the UE implementation, and the value of b should meetthe delay requirement of the current service of the UE; if the UEreporting the channel detection result is triggered by condition 2 orcondition 3, then a=1, b=100. Because the gap between the subframe wherethe eNB sends DCI 5A and the subframe indicated by DCI 5A where PSCCHand PSSCH resource are located should be at least 4 ms, preferably, ifUE reporting the channel detection result is triggered by Condition 2 orCondition 3, in order to provide timely channel detection result to eNB,the period P the UE reports the channel detection result should be lessthan b. For example, if b is 100, and the channel detection result isfed back by the physical layer signaling, the value of P should not begreater than 96. If b is 100, and the channel detection result is fedback by the higher layer signaling, the value of P should not be greaterthan X, where X is less than 96, such as X=95 or 94.

Preferably, when reporting the channel detection result, the UE shouldfurther report the global positioning system (GPS) coordinates of thecurrent location.

If the channel detection mode is implementation I, and it is not foundthat the UE occupies single-subframe resources R_(x,y+k×P) _(step) ,j=1, 2, 3, , , , I1, in I1 detections, then the UE takes single-subframeresources R_(x,y+II×P) _(step) _(k×P) _(step) , k=1, 2, . . . , astransmitting resources for data transmission.

If the channel detection mode is implementation II, and it is not foundthat the UE occupies single-subframe resources

R_(x, y + j × P_(rsvp_TX)),

j=1, 2, 3, . . . I2, in I2 detections, then the UE takes single-subframeresource

R_(x, y + I 2 × P_(rsvp_TX) + k  × P_(rsvp_TX)),

k=1, 2, . . . , as transmitting resources for data transmission.

If the channel detection mode is implementation III, and single-subframeresources R_(x,y+j×Pm), j=1, 2, 3, . . . I3, are not occupied by otherUEs, then the UE determines single-subframe resourcesR_(x,y+I3×Pm×k×Pm), k=1, 2, . . . , as transmitting resources for datatransmission.

If the channel detection mode is implementation IV, and single-subframeresource R_(x,y) k=1, 2, . . . , as transmitting resources for datatransmission.

If the channel detection mode is implementation IV, and single-subframeresource, R_(x,y+j×P) _(rsvp_TX) , j=1, 2, 3, . . . , as transmittingresources for data transmission.

If the channel detection mode is implementation V, and single-subframeresources

R_(x, y + I₄ × P_(rsvp_TX) + j × P_(rsvp_TX)):,

j=0, 1, 2, . . . , are not occupied by other UEs, then the UE selectssingle-subframe resources

R_(x, y + I₄ × P_(rsvp_TX) + j × P_(rsvp_TX)),

as transmitting resources for data transmission.

If the channel detection mode is implementation VI, and single-subframeresource R_(x,y) is not occupied by other UEs, then the UE selectssingle-subframe resource R_(x,y+j×P) _(rsvp_TX) , j=1, 2, 3, . . . , astransmitting resources for data transmission.

The UE transmits the PSCCH on a PSCCH resource corresponding to theselected single-subframe resources, and transmits the PSSCH on theselected single-subframe resources.

Case V

In Case V, the UE operates in Mode 3. Under certain condition, the UEreports the channel detection result of the current resource pool to theeNB to assist the eNB in resource allocation. The UE working in Mode 3performs a receiving operation on a resource pool, for example,receiving V2X information and measured CBR from other UE(s), andtherefore, the UE may observe traffic distribution on the resource pool,so that the UE may know which resources are relatively busy, and whichresources are relatively idle in the resource pool. Therefore, the UE inMode 3 may report information on traffic distribution in resource poolto the base station, so as to facilitate the base station schedulingdata transmission of the UE in Mode 3 on relatively idle resources,thereby reducing the impact on users in Mode 4. For example, the aboveinformation on traffic distribution in resource pool may indicate anidle resource period and subframe offset. The present disclosure doesnot limit the specific method for indicating information on trafficdistribution in resource pool. After receiving the bypass resourceallocation indication (that is, DCI 5A) sent by the eNB, the UE sendsPSCCH and PSSCH directly on the resource indicated by DCI 5A or the UEdetermines sending resource according to the method described in CaseIV.

Preferably, a method for the UE assisting the base station to performresource allocation of mode 3 by reporting the detection result isdescribed below. Steps are as follows:

At the first step, if the subframe n satisfies at least one of thefollowing conditions, the UE reports the channel detection result to theeNB in subframe n:

Condition 1: The UE satisfies bypass Buffer Status Report (BSR)condition in subframe n, and the service corresponding to the bypass BSRis a V2X service that the UE intends to send in the current resourcepool.

Condition 2: the subframe n satisfies the channel detection resultreporting configuration indicated by the eNB, that is, (n-Δ) mod P=0,where Δ is the channel detection result reporting subframe offsetindicated by the eNB, P is the channel detection result reportingperiod, the UE determines the value of P according to the eNBindication, pre-configuration or standard definition.

Condition 3: subframe n is the first subframe in which there is uplinkscheduling resource for UE after subframe x, where subframe x is thelatest subframe in which the UE receives an indication of channeldetection result reporting of the eNB. The indication of channeldetection result reporting of the eNB may be RRC layer signaling, MAClayer signaling or physical layer signaling.

Preferably, the channel detection result reported by the UE shouldinclude channel conditions on part or all of the subchannels in thesubframe range [n+a, n+b], and for any one of the reported subchannels,its channel conditions include at least one item of the followinginformation: average S-RSSI on the sub-channel, PSSCH-RSRP on thesub-channel, the priority of PSSCH sent by the UE that reserves thesub-channel, the resource reservation period of the UE that reserves thesub-channel, and the like. For example, if UE reporting the channeldetection result is triggered by the condition 1, the values of a and bare determined by the UE implementation, and the value of b should meetthe delay requirement of the current service of the UE; if the UEreporting the channel detection result is triggered by condition 2 orcondition 3, then a=1, b=100. Because the gap between the subframe wherethe eNB sends DCI 5A and the subframe indicated by DCI 5A where PSCCHand PSSCH resource are located should be at least 4 ms, preferably, ifUE reporting the channel detection result is triggered by Condition 2 orCondition 3, in order to provide timely channel detection result to eNB,the period P the UE reports the channel detection result should be lessthan b. For example, if b is 100, and the channel detection result isfed back by the physical layer signaling, the value of P should not begreater than 96. If b is 100, and the channel detection result is fedback by the higher layer signaling, the value of P should not be greaterthan X, where X is less than 96, such as X=95 or 94.

Preferably, when reporting the channel detection result, the UE shouldfurther report the global positioning system (GPS) coordinates of thecurrent location.

At the second step, the UE sends PSCCH and PSSCH on the resourceindicated by DCI 5A or on the transmission resource determined accordingto the method in Case IV after receiving bypass resource allocationindication (that is, DCI 5A) sent by the eNB.

Through the above method, the UE working in Mode 3 determines theresource occupation and the resource reservation in the current resourcepool by channel detection. After the UE reports the detection result tothe eNB, the eNB may schedule the resource with a relatively highchannel quality to the UE in Mode 3 for data transmission, therebyreducing the interference between user in Mode 3 and user in Mode 4.

FIG. 2 is a block diagram of user equipment (UE) which performs aresource selection or reselection method in vehicle tovehicle/pedestrian/infrastructure/network or Vehicle to Everything (V2X)communication according to an embodiment of the present disclosure.Referring to FIG. 2, the equipment comprises: a detection module 21, aresource selection or reselection module 22 and a transmitting module23.

The detection module is used for detecting PSCCH transmitted by otherUEs. The detection module may detect the SCI x on all PSCCH resources ina transmitting resource pool currently selected by the UE, or onlydetect the SCI x on some PSCCH resources in the transmitting resourcepool currently selected by the UE, for example, positions of the somePSCCH resources determined by receiving signalling of an eNB.

The resource selection or reselection module is configured to selectsingle-subframe resources from single-subframe resources which do notoverlap with single-subframe resources reserved by the detected PSCCH.

According to one embodiment of the present disclosure, if the detectedSCI x is in a particular format, then single-subframe resources areselected from single-subframe resources which do not overlap withsingle-subframe resources reserved by the detected PSCCH.

According to another embodiment of the present disclosure, if thedetected SCI x is in a particular PSCCH format, and a value prio_(RX) ofa priority field contained in the SCI x is greater than a particularvalue, then single-subframe resources are selected from single-subframeresources which do not overlap with single-subframe resources reservedby the detected PSCCH.

For example, the particular PSCCH format is SCI 1 defined in 3GPPrelease 14, or a PSCCH format different from the SCI 1 defined in 3GPPrelease 14, or a format which has the same number of bits as the SCI 1defined in 3GPP release 14, and the meaning of each field is the same,but one or more bits in reserved bits field are 1.

According to yet another embodiment of the present disclosure, theresource selection or reselection module further measures sidelinkreference signal received power of a PSSCH (PSSCH-RSRP) scheduled by SCIx, if the PSSCH-RSRP is higher than a particular threshold, thensingle-subframe resources are selected from single-subframe resourceswhich do not overlap with single-subframe resources reserved by thedetected PSCCH.

The transmitting module transmits physical sidelink shared channel(PSSCH) on the selected single-subframe resources.

In the following, unless specifically explained, the first UE refers toa UE which performs the channel detection and resource selection orreselection, and the second UE refers to the UE detected by the firstUE. In embodiments of the present disclosure, a slot refers to a minimumtime unit for the first UE to transmit PSSCH. In other words, theminimum time unit that the first UE transmits the PSSCH is referred toas a slot. This slot does not refer to the time resource size in the LTEsystem. A physical resource block (PRB) refers to a minimum frequencyunit for the first UE to transmit PSSCH, i.e., the minimum frequencyunit that the first UE transmits the PSSCH is referred to as a PRB,which is not the resource block size in the LTE.

In current LTE-based V2X communication systems, since both the lowestdata transmission delay and the highest transmission reliability cannotmeet the requirements of V2X application scenarios newly defined by3GPP, the V2X communication mechanism needs to be improved, so as toincrease the data transmission reliability on the premise of ensuring alower data transmission delay, thereby meeting the requirement of thenewly defined V2X application scenarios. Therefore, various embodimentsof the present disclosure provide a sidelink resource allocation methodcapable of ensuring low delay and high reliability. As shown in FIG. 3,the method includes the following.

In step S301, a first UE determines a SideLink Grant (SLG).

In embodiments of the present disclosure, the SLG of the first UEincludes information such as position information of M PSSCHtransmission resources, modulation and coding scheme for transmitting aTransmission Block (TB), etc. The M PSSCH transmission resources areused for M times of transmission of one TB, M is a specified value andmay be defined by specifications, or configured by eNB or configured inadvance. If the first UE is able to occupy multiple time-frequencyresources of one SLG semi-persistently with a certain period, the SLGmay further includes the length of the period for the semi-persistentoccupation.

The first UE may determine the time-frequency position information ofthe multiple PSSCHs for the multiple times of transmission of one TB inthe SLG through receiving one or more downlink control signaling of thebase station, or the first UE may determine the time-frequency positioninformation of the multiple PSSCHs through channel detection. Thetime-frequency resources of the multiple PSSCHs may have a predefinedbinding relationship. In this case, the group of PSSCH time-frequencyresources with the binding relationship is called a PSSCH resourcepattern.

If there is no predefined binding relationship between the PSSCHtime-frequency resources and the PSCCH resources scheduling the PSSCH,when the first UE determines the SLG through receiving the one or moredownlink control signaling of the base station, the one or more downlinkcontrol signaling of the base station shall further indicate the PSCCHtransmission resources, when the first UE determines the SLG via channeldetection, the first UE selects one PSCCH transmission resourceaccording to a channel detection result.

The modulation and coding scheme for transmitting the TB may bedetermined according to information such as priority of the data to betransmitted by the UE, moving speed, carrier frequency and currentchannel busy condition, etc.

In step S302, the first UE transmits the PSSCH according to the SLG.

The PSSCH is scheduled by the transmitted PSCCH.

In embodiments of the present disclosure, the PSCCH and the PSSCHscheduled by the PSCCH may be transmitted in a time division manner,e.g., transmitted on different symbols of the same slot, or transmittedin different slots. In addition, the PSCCH and the PSSCH scheduled bythe PSCCH may also be transmitted in a frequency division manner, e.g.,transmitted on different physical resource blocks (PRBs) of the sameslot. There may be a binding relationship between the time-frequencyresources of the PSSCH and the resources of the PSCCH scheduling thePSSCH, e.g., it may be predefined that the first PRB in the PSSCHtransmission resources is used for transmitting the PSCCH.

For facilitating the understanding of the present disclosure, the abovetechnical solution is described with reference to some detailedapplication scenarios.

Embodiment 1

In this embodiment, the first UE determines the position information ofmultiple PSSCH time-frequency resources in the SLG through receiving oneor more downlink control signaling of the base station, and there is nobinding relationship between the multiple PSSCH time-frequency resourcescontained in the SLG.

Hereinafter, the resource allocation manner provided by this embodimentis described with reference to two situations.

Determining the SLG via one downlink control signaling

If the first UE determines the SLG through receiving one downlinkcontrol signaling of the base station, the downlink control signalingshould include the position of multiple PSSCH time-frequency resourcesused for M times of transmissions of one TB. In particular, the downlinkcontrol signaling includes at least the following information:

positions of slots where the time-frequency resources used for thesecond time till the M-th time transmission are located;

frequency-domain positions of the time-frequency resources used for eachtime transmission and the number of frequency-domain resources containedin the time-frequency resources for each time transmission; wherein thefrequency positions of the time-frequency resources for the M times oftransmission may be different, but the number of frequency-domainresources contained in the time-frequency resources for the M times oftransmission is the same.

In this situation, if the first UE receives the downlink controlsignaling in slot n1, the first slot which is after slot n1+k andbelonging to the current resource pool of the first UE is the slot wherethe resource for first time transmission in the SLG is located, whereink is a specified integer and is determined according to the processingcapability of the first UE and the slot configuration of the currentcarrier. The first UE may determine the value of k according toconfiguration of the base station or definition of the specifications.The first UE determines configuration of the resource pool according tosignaling of the base station. The SLG further indicates positions ofthe slots where time-frequency resources for the other M−1 times oftransmission are located. For example, |log₂ C_(T) ^(M-1)| bits in theSLG indicate the positions of slots wherein the time-frequency resourcesfor the second time till the M-th time transmission are located, thepositions indicate M−1 slots within slots [n1+k+1, n1+k+T], wherein T isa specified value configured by the base station or defined byspecifications.

II. Determining the SLG Through Multiple Downlink Control Signaling.

If the first UE determines the SLG through receiving multiple downlinkcontrol signaling of the base station, each downlink control signalingshould include positions of PSSCH time-frequency resources used for Ntimes of transmission of one TB, wherein N≤M, e.g. N=1 or 2. In thissituation, if the UE receives downlink control signaling A in slot n2,the first PSSCH transmission resource indicated by the downlink controlsignaling A is located in slot n2+k. In some embodiments, each downlinkcontrol signaling includes a downlink control signaling index, the indexis within [0, M/N−1], the PSSCH transmission resources indicated by thecontinuous M/N downlink control signaling indexed from 0 to M/N−1 forman SLG.

In addition, after determining the SLG and before transmitting the PSCCHand the PSSCH, in some embodiments, an occupation manner of thetime-frequency resources in the SLG may be determined. For example, theoccupation manner may be semi-persistent occupation with a predefinedtime interval or one-time occupation. Thus, the first UE maysemi-persistently occupy the time-frequency resources in the SLG withthe time interval predefined by the base station. The first UE mayreceive the high-layer signaling (RRC layer signaling) of the basestation to determine the time interval. Or, the first UE may determinethe time interval according to the one or more downlink controlsignaling indicating the SLG. Or, the first UE may occupy thetime-frequency resources in the SLG only once, i.e., only transmit thePSSCH using the time-frequency resources in the SLG for one time.

As to the occupation manner of the time-frequency resources, the firstUE may indicate it via the one or more downlink control signalingindicating the SLG. The first UE determines whether the resources in theSLG can be semi-persistently occupied or can be occupied one timeaccording to the corresponding downlink control signaling. For example,the downlink control signaling indicating semi-persistent occupation andone-time occupation may adopt different scrambling sequences. The firstUE determines the scrambling sequence used by the downlink controlsignaling via blind detection, and then determines the type of the SLG(semi-persistent occupation or one-time occupation).

In this embodiment, the PSCCH transmitted by the UE may indicate onlythe time-frequency resource position of the currently scheduled PSSCH,or indicate the position of the currently scheduled PSSCH and the nextPSSCH transmission, or indicate the position of M PSSCH transmissionresources for transmitting one TB at the same time.

Embodiment 2

In this embodiment, there is a binding relationship between the multiplePSSCH time-frequency resources contained in the SLG, i.e. there is apredefined PSSCH resource pattern. The first UE determines the resourcepattern of the SLG through receiving control signaling of the basestation.

In some embodiments, the resource pattern may be defined as M PSSCHtransmission resource units across a time period T and a frequency rangeF (referred to as a resource pattern space), it repeats each time periodT, the first PSSCH transmission resource unit and the last PSSCHtransmission resource unit contained in one resource pattern have atime-domain gap less than or equal to the sum of a maximum tolerateddelay for the data transmission of the first UE and the time requiredfor coding the PSSCH. Within one resource pattern space, each resourcepattern corresponds to a unique resource pattern index. Furthermore,there is at least one slot position difference between the PSSCHtransmission resources of any two resource patterns. In this embodiment,the first UE may determine the resource pattern space through receivingthe signaling of the base station.

FIG. 4 provides a possible resource pattern. As shown in FIG. 4, thepattern controls 6 slots in time and 5 PSSCH transmission resource unitsin frequency, M=2. In this embodiment, the resource pattern index

${r = {\sum\limits_{t = 0}^{M - 1}{\langle\begin{matrix}{T - n_{t}} \\{M - t}\end{matrix}\rangle}}},$

wherein n_(t)∈[1,T], denoting a time-domain index of the t-th PSSCHtransmission resource unit in the pattern space. For a resource patternwith index r, the frequency-domain indexes of its PSSCH transmissionresources are

${m_{j} = {\sum\limits_{\underset{i \neq j}{i = 0}}^{M - 1}{\langle\begin{matrix}{T - n_{i} - \delta} \\{M - i - \delta}\end{matrix}\rangle}}},{\delta = \{ {\begin{matrix}1 & {n_{i} < n_{j}} \\0 & {others}\end{matrix},{j \in \lbrack {0,{M - 1}} \rbrack},{m_{j} \in {\lbrack {0,{F - 1}} \rbrack.}}} }$

According to the relationship between the time-domain andfrequency-domain indexes and the resource pattern index and the resourcepattern index r, it is possible to determine a unique resource patternin the resource pattern space.

In this embodiment, the downlink control signaling of the base stationmay include the resource pattern index r of the resource pattern of theSLG, if the first UE receives the downlink control signaling of the basestation in slot n3, the first UE determines the first resource patternwith index r after slot n3+k as the allocated SLG resources.

Similarly as embodiment 1, the first UE may determine the occupationmanner of the resources in the SLG, e.g., semi-persistent occupation orone-time occupation. In particular, the first UE may semi-persistentlyoccupy the time-frequency resources in the SLG with the time intervalpredefined by the base station. The first UE may receive the high-layersignaling (RRC layer signaling) of the base station to determine thetime interval. Or, the first UE may determine the time intervalaccording to the one or more downlink control signaling indicating theSLG. In some embodiments, the time interval is an integer times of theresource pattern space periodicity T. Or, the first UE may occupy thetime-frequency resources in the SLG only once, i.e., only transmit thePSSCH using the time-frequency resources in the SLG for one time. Thefirst UE determines whether the resources in the SLG can besemi-persistently occupied or can be occupied one time according to theone or more downlink control signaling indicating the SLG. For example,the downlink control signaling indicating semi-persistent occupation andone-time occupation may adopt different scrambling sequences. The firstUE determines the scrambling sequence used by the downlink controlsignaling via blind detection, and then determines the type of the SLG(semi-persistent occupation or one-time occupation).

In this embodiment, the PSCCH transmitted by the UE may indicate theresource pattern index for the PSSCH scheduled by the PSCCH, via anexplicit or implicit manner. For example, there is a fixed mappingrelationship between positions of the PSCCH frequency resources and thepositions of the RBs occupied by the PSSCH transmission resource patternin the current slot. Thus, the index of the resource pattern may beimplicitly indicated by the frequency resource index of the PSCCH.

Embodiment 3

In this embodiment, the first UE determines position information ofmultiple PSSCH time-frequency resources in the SLG through channeldetection. There is no binding relationship between the multiple PSSCHtime-frequency resources contained in the SLG.

Suppose that the first UE performs SLG determination operation in slotn4. If PRB group (RBG) is configured, and the RBG is taken as a resourceallocation unit (i.e., downlink resource allocation manner 0 defined incurrent LTE specifications), the first UE regards LRBG RBGs in any slotbelonging to the current resource pool of the first UE and within[n4+T1, n4+T2] as a candidate single-slot resource, as shown in FIG. 5,referred to as single-slot resource format 0 hereinafter. If RBG isconfigured, and the RBG is taken as a resource allocation unit, but ineach RBG only one PRB with the same index can be allocated (i.e. thedownlink resource allocation manner 1 defined in current LTEspecifications), the first UE regards the i-th PRB in {tilde over(L)}_(RBG) RBGs in any slot which is belonging to the current resourcepool of the first UE and within [n4+T1, n4+T2] as a candidatesingle-slot resource, i=1, 2, . . . , NRBG, NRBG denotes the number ofPRBs in one RBG, as shown in FIG. 6, hereinafter referred to assingle-slot resource format 1. If RBG is not configured, the first UEtakes LRB PRBs in any slot which is belonging to the current resourcepool of the first UE and within [n4+T1, n4+T2] as a candidatesingle-slot resource, hereinafter referred to as single-slot resourceformat 2. The values of T1 and T2 are determined according toimplementation of the UE. [n4+T1, n4+T2] is referred to as a resourceselection window, LRBG, {tilde over (L)}_(RBG), or LRB are determined byhigher layer of the first UE, e.g., MAC layer of the first UE. The totalnumber of single-slot resources in the resource selection window isdenoted by Mtotal, Mtotal candidate single-slot resources constitute aset S.

Hereinafter, the detailed procedure for determining the SLG based onchannel detection in this embodiment of the present disclosure isdescribed.

Suppose that the PSSCH and the PSCCH scheduling the PSSCH aretransmitted in the same slot, and a second UE semi-persistently occupieseach PSSCH transmission resource with a predefined time interval, thefirst UE may detect in slots in a channel detection window before slotn4, wherein the channel detection window is defined by specifications,e.g., slots n4−1000, n4−999, . . . , n4−1 may be defined as the channeldetection window. For any slot detected by the first UE, the first UEdecodes the PSCCH in the slot, determines the number of successfullydecoded PSCCH in each slot, and measures a reference signal receivingpower of the scheduled PSSCH, priority of data transmitted on the PSSCHand resource reservation interval for the PSSCH transmission resourcesaccording to the decoded PSCCH. In addition, in each detected slot, anaverage receiving energy of each RBG or each RB in the slot may bemeasured. In particular, for the single-slot resource format 0, thefirst UE measures the average receiving energy of each RBG in thedetected slot. For the single-slot resource format 1 or single-slotresource format 2, the first UE measures the average receiving energy ofeach RB in the detected slot.

The first UE estimates, according to a measurement result in the channeldetection window, the number of second UEs which may perform PSCCHtransmission in each candidate slot in the resource selection window,the PSSCH reference signal receiving power on the candidate single-slotresource, and the average receiving energy of each RB or each RBG. Theestimation may be performed similarly as a conventional method, which isdescribed in the following.

The first UE may estimate the number of second UEs which may transmitPSCCH in each candidate slot in the resource selection window asfollows: for any slot in the resource selection window, if the first UEsuccessfully detects PSCCH in slot y in the channel detection window,and the PSCCH indicates a resource reservation interval p and y+p=x, thefirst UE regards that the second UE which transmits the PSCCH will alsotransmit PSCCH in slot x.

The first UE may estimate the PSSCH reference signal receiving power ona candidate single-slot resource in the resource selection window asfollows: if the first UE successfully detects the PSCCH in slot y of thechannel detection window, and measures the reference signal receivingpower of the PSSCH scheduled by the PSCCH, suppose that the PSCCHindicates a resource reservation interval p and slot y+p still belongsto the resource selection window, the first UE regards that the secondUE which transmits the PSSCH will also transmit PSSCH on the samefrequency position in slot y+p, and the reference signal receiving powerof the PSSCH is the same.

The first UE may estimate the average receiving power of each RB or eachRBG in the resource selection window as follows: for any RB or RBG inany slot x in the resource selection window, the first UE regards thatan average value of the receiving energies measured on the same RB orRBG in slots x−j*Pm as the average receiving energy of the RB or the RBGin the slot x. Pm denotes a measurement interval, it may be defined byspecifications, or configured by the eNB or preconfigured, e.g., Pm is100, or equal to a reservation interval for the data to be transmittedby the first UE, or equal to a minimum resource reservation intervalallowed by the current resource pool; j includes all positive integerswhich make x−j*Pm belonging to the channel detection window.

Then, the first UE selects from set S, according to the above estimationresult, M single-slot resources in which the second UE occupiesrelatively less resources to determine the SLG. The selection may beconfigured according to a practical requirement. The principle forselecting the M single-slot resources is to select those with fewerresources occupied by other UEs as much as possible. As such, the dataof the first UE may have a little probability to collide with other UEsand lost, and the data transmission reliability may be increased. Inparticular, M single-slot resources on which resources occupied by thesecond UE is lower than a defined requirement may be selected. Herein,the defined requirement may be either an explicit requirement, or arequirement implicitly generated based on the selection of the Msingle-slot resources. In addition, the second UE may be not a singleone, but include multiple UEs detected by the first UE. Hereinafter, oneselection manner is provided.

In particular, the first UE may select M single-slot resources locatedin different slots from set S to determine the SLG according to one ofthe following steps:

The first UE selects X % slots with minimum number of successfullydecoded PSCCH in the resource selection window as candidate slots;

The first UE excludes single-slot resources with PSSCH reference signalpower higher than a specified threshold from the single-slot resourcesof the candidate slots according to the PSSCH reference signal receivingpower and the priority of the data transmitted by the PSSCH, thespecified threshold is relevant to the priority of the data transmittedby the PSSCH and the priority of the data to be transmitted by the firstUE.

The first UE sorts, after some single-slot resources are excludedthrough step 2, the remaining single-slot resources of the candidateslots according to their receiving energies, selects M single-slotresources located in different slots from Y % single-slot resources withlowest receiving energy, and takes the selected M single-slot resourcesas the M PSSCH transmission resources of the SLG; wherein when selectingthe M single-slot resources from the Y % single-slot resources withlowest receiving energy, the selection may be performed according to arequirement, e.g., randomly select with equal probability.

X and Y are both specified values, which may be configured by the basestation, preconfigured or defined by specifications. The selected Msingle-slot resources are located in different slots.

The first UE may semi-persistently occupy the time-frequency resourcesof the SLG with a specified interval. The specified interval may bedetermined by a higher layer of the UE (e.g., MAC layer of the UE). Inthis embodiment, the PSCCH transmitted by the UE may indicate merely thetime-frequency resource positions of the currently scheduled PSSCH, orindicate the resource positions of both the currently scheduled PSSCHand a next PSSCH, or indicate the positions of M PSSCH transmissionresources used for one TB transmission at the same time.

Embodiment 4

In this embodiment, there is a binding relationship between the multiplePSSCH time-frequency resources contained in the SLG, i.e., a PSSCHresource pattern is predefined. The first UE determines the resourcepattern in the SLG by channel detection.

In some embodiments, the resource pattern may be defined as M PSSCHtransmission resource units across a time period T and a frequency rangeF (referred to as a resource pattern space), it repeats each time periodT, the first PSSCH transmission resource unit and the last PSSCHtransmission resource unit contained in one resource pattern have atime-domain gap less than or equal to the sum of a maximum tolerateddelay for the data transmission of the first UE and the time requiredfor coding the PSSCH. Within one resource pattern space, each resourcepattern corresponds to a unique resource pattern index. Furthermore,there is at least one slot position difference between the PSSCHtransmission resources of any two resource patterns. In this embodiment,the first UE may determine the resource pattern space through receivingthe signaling of the base station.

Suppose that the first UE performs the SLG determination operation inslot n4, then the first UE should regard any resource pattern whosestarting subframe and ending subframe are both located within slots[n4+T1, n4+T2] as a candidate resource pattern, as shown in FIG. 7. Thevalues of T1 and T2 are determined according to implementation of theUE. [n4+T1, n4+T2] is referred to as a resource selection window. Thetotal number of candidate resource patterns in the resource selectionwindow is denoted by M_(total) ^(p), M_(total) ^(p) candidate resourcepatterns form a set SP.

Hereinafter, the procedure of determining the SLG according to thechannel detection in this embodiment is described.

Suppose that the second UE semi-persistently occupies a resource patternwith a specified time interval, the first UE may detect in slots in thechannel detection window before slot n4, wherein the channel detectionwindow is defined by specifications, e.g., slots n4−1000, n4−999, . . ., n4−1 may be defined as the channel detection window. For a slotdetected by the first UE, the first UE decodes the PSCCH in the slot,measures reference signal average receiving power of multiple PSSCHs onthe resource pattern, priority of data transmitted by the PSSCHs and aresource pattern reservation interval according to the decoded PSCCH.The first UE further measures an average receiving energy of theresource pattern in the channel detection window.

The first UE estimates, according to the measurement result in thechannel detection window, PSSCH reference signal receiving power of eachcandidate resource pattern and average receiving energy of eachcandidate resource pattern in the resource selection window. Theestimation may be performed similarly as a conventional method, but theresource pattern is taken as a detection unit. The procedure isdescribed in the following.

The first UE estimates the PSSCH reference signal receiving power of thecandidate resource pattern in the resource selection window as follows:if the first UE successfully detects the PSCCH scheduling resourcepattern Q in the channel detection window, and measures the PSSCHreference signal receiving power on the resource pattern Q, suppose thatthe PSCCH indicates a resource reservation interval p, the first UEregards that the second UE transmitting the above PSSCH will alsotransmit PSSCH on the same resource pattern after p slots, and the PSSCHreference signal receiving power on that resource pattern is the same.

The first UE may estimate the average receiving energy of each resourcepattern in the resource selection window as follows: for any resourcepattern Q in the resource selection window, the first UE regards anaverage of receiving energies measured on resource patterns with aninterval of integer times of Pm starting from the resource pattern Q asthe average receiving energy of the resource pattern Q. Pm denotes ameasurement interval, it may be defined by specifications, or configuredby the eNB or preconfigured. For example, Pm may be equal to 100, orequal to a reservation interval for the data to be transmitted by thefirst UE, or equal to a minimum resource reservation interval allowed bythe current resource pool.

Then, in the set Sp, the first UE selects according to the aboveestimation result a resource pattern with less resource being occupiedby the second UE to determine the SLG. The detailed selection manner maybe configured according to a practical requirement. The principle forthe selection is to select those with fewer resources occupied by otherUEs as much as possible. As such, the data of the first UE may have alittle probability to collide with other UEs and lost, and the datatransmission reliability may be increased. In particular, the resourcepattern on which resources occupied by the second UE is lower than adefined requirement may be selected. Herein, the defined requirement maybe either an explicit requirement, or a requirement implicitly generatedbased on the selection of the resource pattern. In addition, the secondUE may be not a single one, but include multiple UEs detected by thefirst UE. Hereinafter, one selection manner is provided.

In particular, the first UE may select resource pattern from set SP todetermine the SLG according to one of the following steps:

The first UE excludes resource patterns with PSSCH reference signalaverage receiving power higher than a specified threshold from theresource patterns of the set SP according to the estimated PSSCHreference signal average receiving power and the priority of the datatransmitted by the PSSCH on the resource patterns in the set SP, thespecified threshold is relevant to the priority of the data transmittedby the PSSCH and the priority of the data to be transmitted by the firstUE.

2. The first UE sorts the remaining resource patterns of the set SPaccording to their average receiving energies, selects one resourcepattern from Y % resource patterns with lowest receiving energy, andtakes the selected resource pattern as the PSCCH transmission resourcesof the SLG; wherein when selecting the resource pattern from the Y %resource patterns with lowest receiving energy, the selection may beperformed according to a requirement, e.g., randomly select with equalprobability.

Y is a specified value, which may be configured by the base station,preconfigured or defined by specifications.

The first UE may occupy the resource pattern of the SLGsemi-persistently with a specified time interval, the specified timeinterval may be determined by a higher layer of the UE (e.g., MAC layerof the UE).

In this embodiment, the PSCCH transmitted by the UE may indicate theindex of the transmission resource pattern of the PSSCH scheduled by thePSCCH. The index may be indicated explicitly or implicitly. For example,there may be a fixed mapping relationship between the positions of thePSCCH frequency resources and the positions of the RBs occupied by thePSSCH transmission resource pattern in the current slot. Thus, the indexof the resource pattern may be implicitly indicated by the frequencyresource index of the PSCCH.

The above describes the resource allocation method in the sidelinkcommunications provided by the embodiments of the present disclosure.Some embodiments of the present disclosure also provide a resourceallocation apparatus, applicable for implementing the above resourceallocation method.

FIG. 8 is a block diagram illustrating a structure of the apparatusaccording to some embodiments of the present disclosure. As shown inFIG. 8, the apparatus includes: a determining unit 801 and atransmitting unit 802.

The determining unit is configured to determine a sidelink grant SLG.The SLG includes positions of M PSSCH transmission resources, the MPSSCH transmission resources are used for M times of transmission of aTransmission Block (TB), M is an integer. The transmitting unit isconfigured to transmit a PSCCH and the PSSCH according to the determinedSLG.

According to the resource allocation method and apparatus provided bythe embodiments of the present disclosure, it is possible to ensure thedata transmission delay as well as decrease the half-duplex impactbetween different UEs, so as to improve data successful receiving rate.

In the following, unless specifically explained, the first UE refers toa UE which performs the channel detection and resource selection orreselection, and the second UE refers to the UE detected by the firstUE.

In order to increase the system capacity and data rate of the V2Xcommunication, the UE needs to implement the V2X communication viamultiple sidelink carriers. In order to solve problems such ashalf-duplex restriction and In Band Emission (IBE) interferences existin the multi-carrier sidelink communication, various embodiments of thepresent disclosure provide a resource selection or reselection method inV2X communication. This method is able to increase the probability thatthe UE selects the frequency resources of the same subframe duringresource selection or reselection on multiple carriers, so as to solvethe half-duplex restriction and IBE interference in the multi-carriersidelink communication environment, and improve the performance of theV2X system.

FIG. 9 is a flowchart illustrating a resource selection or reselectionmethod according to various embodiments of the present disclosure. Asshown in FIG. 9, the method includes the following.

At block S901, a first UE determines a carrier set C available forresource selection or reselection.

The carrier set C may include one or more carriers. The UE may determinethe available candidate carriers from a configured or pre-configured setCS of all carriers according to a current service type. Further, the UEmay determine one or more carriers available for channel selection orreselection from the candidate carriers according to information such asChannel Busy Ratio (CBR) of each candidate carrier. In variousembodiments, the first UE may select one or more carriers with thelowest CBR from the carrier set CS, or select one or more carriers withCBR lower than a certain threshold from the set CS, wherein thethreshold may be defined by specifications, or configured by an eNB orpre-configured. Suppose that the number of carriers in the carrier set Cis N1.

The UE may determine the above set CS of all carriers according tosignalling SystemInformationBlockType21 or RRCConnectionReconfigurationdefined in 3GPP TS 36.331 V14.3.0. In this case, multiple or allcarriers in the set CS may correspond to the same parameter typeTxSync,or, each carrier corresponds to its own parameter typeTxSync, but thevalues of all typeTxSync are same. For example, the carriers in the setCs are divided into multiple carrier groups, each carrier group includesone or more carriers, the one or more carriers in one carrier groupcorrespond to the same typeTxSync. The value of the typeTxSync may beeNB or GNSS, denoting that the carriers preferably take the eNB or GNSSas a reference synchronization source. In addition, the UE may determinethe above set Cs of all carriers via pre-configuration. In this case,the multiple or all carrier in the Cs may correspond to the sameparameter syncPriority, or, each carrier corresponds to its respectiveparameter syncPriority, but the values of them are the same. Forexample, the carriers in the set Cs are divided into groups, each groupinclude one or more carriers, the one or more carriers in each groupcorrespond to the same syncPriority. The value of syncPriority may beeNB or GNSS, denoting that the multiple carriers preferably take the eNBor GNSS as the reference synchronization source.

According to various embodiments of the present disclosure, if thecarrier set C includes one or multiple carriers, the configuration ofSidelink Synchronization Signal (SLSS) subframes on some or all carriersare the same. For example, SLSS transmission periodicity on each carrierin the same frequency band in the carrier set C, number of SLSSsubframes in each SLSS transmission periodicity, and the offset of eachSLSS transmission subframe in each SLSS transmission periodicity are thesame, so as to ensure that the number and positions of subframesavailable for transmitting the PSCCH and PSSCH are the same on multiplecarriers, and avoid that one subframe on one carrier overlaps withsubframes on another one or more carriers. Or, if the carrier set Cincludes one or more carriers, the pre-configuration of SidelinkSynchronization Signal (SLSS) subframes on some or all carriers in thecarrier set C should be the same. If subframe x is an SLSS subframeaccording to pre-configuration information, subframe x cannot be putinto resource pool, i.e., bit map for resource pool configuration cannotmap to subframe x.

According to another embodiment of the present disclosure, if thecarrier set C includes one or multiple carriers, Sidelinksynchronization signal (SLSS) subframes may be configured differently onsome or all carriers. In this situation, if subframe x is an SLSSsubframe on any one of the carriers, subframe x on all carriers cannotbe put into resource pool, i.e., bit map for resource pool configurationcannot map to subframe x. For example, for multiple interfering carriersin carrier set C, if the SLSS transmission periodicity, the number ofSLSS subframes in each SLSS transmission periodicity and the offset ofeach SLSS transmission subframe in each SLSS transmission periodicityare not the completely same, all SLSS transmission subframes on themultiple interfering carriers cannot used for the resource poolconfiguration. The first UE may regard the carriers in the samefrequency band as interfering carriers, or regards multiple carriersadopting the same transmission or receiving radio link as interferingcarriers, or the first UE may determine the multiple interferingcarriers according to configuration signaling or pre-configuration ofthe eNB. Or, if the carrier set C includes one or more carriers, thepre-configuration for the SLSS subframe on some or all carriers may bedifferent. In this case, according to the pre-configuration informationof each carrier, if subframe x is an SLSS subframe on any carrier,subframe x on all carriers cannot be put into the resource pool, i.e.,bit map for resource pool configuration cannot map to subframe x.

According to another embodiment of the present disclosure, if thecarrier set C includes one or multiple carriers, for some or allcarriers of the carrier set C, the SLSS transmission subframes on thesecarriers and the resource are configured independently.

In some embodiments, if the carrier set C includes multiple carriers,for each carrier:

In block S902, the first UE determine a candidate single-subframeresource set S from the carrier set C.

In various embodiments, if sub-channels included in a single-subframeresource are located on the same carrier, it is referred to as asingle-carrier single-subframe resource. In this situation, it isdefined that a single-subframe resource R_(x,y) ^(c) on any carrier c inthe carrier set C includes L_(subCH) ^(c) continuous sub-channelsstarting from sub-channel x in subframe t_(y) ^(SL), wherein

y denotes a relative index of subframe t_(y) ^(SL) in the resource pool;

L_(subCH) ^(c) is determined by a higher layer of the UE (e.g. MAClayer), and denotes the number of sub-channels used for one PSSCHtransmission on carrier c, c=0, 1, . . . , N1−1.

If the UE performs resource selection or reselection in subframe n, theUE regards L_(subCH) ^(c) continuous sub-channels in subframes belongingto the resource pool within [n+T1, n+T2] on carrier c as candidatesingle-subframe resources, wherein the determination of T1 and T2 aresubject to the implementation of the UE. Assume that the total number ofsingle-subframe resources on carrier c is M_(total) ^(c), the M_(total)^(c) candidate single-subframe resources constitute a set SC. In variousembodiments, a union of single-carrier single-subframe resource sets ofthe carriers in the carrier set C forms the candidate single-subframeresource set S.

In various embodiments, the carriers in the carrier set C are dividedinto one or more carrier groups, and one carrier group includes one ormore carriers. For example, carriers belonging to the same frequencyband in the carrier set C are in the same carrier group. In thissituation, subchannels included in one single-subframe resource may belocated on multiple carriers in one carrier group, which is referred toas a carrier-group single-subframe resource. The carrier group may beconfigured by the eNB or configured in advance, or may be determined bya higher layer of the UE (e.g. UE MAC layer). Suppose that the carrierset C includes R carrier groups, the carrier group G includes M1carriers, wherein G=0, 1, . . . , R−1, M1≤N, and M1 may be equal to 1.The carriers in the carrier group are respectively g0, g1, . . . gM1−1,then one carrier-group single-subframe resource R_(x) _(p) _(,y) ^(G) incarrier group G is defined as L_(subCH) ^(g) ⁰ continuous subchannelsstarting from subchannel x_(g) ₀ on carrier g0 of subframe t_(y) ^(SL),L_(subCH) ^(g) ¹ continuous subchannels starting from subchannel x_(g) ₁on carrier g1 of subframe t_(y) ^(SL), . . . , and L_(subCH) ^(g)^(M1-1) continuous subchannels starting from subchannel x_(g) _(M1-1) oncarrier gM1−1 of subframe t_(y) ^(SL), as shown in FIG. 10; wherein

y denotes a relative index of the subframe t_(y) ^(SL) in the resourcepool;

L_(subCH) ^(g) ¹ is determined by a UE physical layer and meets

${{\sum\limits_{i = 0}^{i = {{M\; 1} - 1}}L_{subCH}^{g_{i}}} = L},$

L is determined by the higher layer of the UE (e.g. MAC layer), i=0, 1,. . . , M1−1; or, L_(subCH) ^(g) ¹ is determined by the higher layer ofthe UE, e.g., determined by the UE MAC layer. It should be noted that,one or more of L_(subCH) ^(g) ⁰ , L_(subCH) ^(g) ¹ , . . . , andL_(subCH) ^(g) ^(M1-1) may be 0.

If the UE performs resource selection or reselection in subframe n, theUE regards L_(subCH) ^(g) ⁰ , L_(subCH) ^(g) ¹ , . . . , L_(subCH) ^(g)^(M1-1) continuous subchannels respectively on carriers g0, g1, . . .gM1−1 in any subframe belonging to the resource pool and within [n+T1,n+T2] on the carrier group G as the candidate single-subframe resources,wherein the values of T1 and T2 are subject to the implementation of theUE. Assume that the total number of single-subframe resources in carriergroup G is M_(total) ^(G), the M_(total) ^(G) candidate single-subframeresources constitute a set SG. In some embodiments, a union of thesingle-subframe resources of all carrier groups in the carrier set Cforms the candidate single-subframe resource set S.

At block S903, the first UE excludes some candidate single-subframeresources from the set S.

It should be noted that, this block is optional. If this block is notexecuted, the exclusion operation is not performed to thesingle-subframe resources in the set S. Accordingly, in followingprocessing, operations performed with respect to remainingsingle-subframe resources in sets S, SC and SG, are adjusted to beperformed to the sets S, SC and SG.

Suppose that the UE performs resource selection in subframe n.

Firstly, the UE may determine some candidate single-subframe resourcesto be excluded from the set S according to a determined receivingoperation in a future subframe. That is, if the UE has determined toperform a receiving operation on one or more carriers in one or moresubframes after subframe n, the UE may exclude some candidatesingle-subframe resources which overlap or conflict with the above oneor more subframes from the set S. In particular, without lossgenerality, suppose that the UE has determined to perform a receivingoperation in subframe m after subframe n on carrier c. For any subframey containing single-subframe resources in the set S, if there is avariable j∈{0, 1, . . . , C_(rexel)−1} which makes the single-subframeresource y+j×P_(rsvp_TX) overlap with subframe m, wherein Cresel denotesthe number of times that resource is to be reserved after resourcereselection, P_(rsvp_TX) denotes an assumed resource reservation periodused for determining available candidate single-subframe resourcesindicated by higher layer of the UE, the first UE excludes allsingle-subframe resources in subframe y on all carriers interfering withcarrier c from the set S. The first UE may determine that all carriersin the same frequency band with carrier c are carriers interfering withcarrier c, or determines carriers using the same transmission orreceiving radio link with carrier c as carriers interfering with carrierc, or the first UE may determine the carriers interfering with carrier caccording to configuration signaling of the eNB or a pre-configuration.The determined receiving operation to be performed by the UE includesbut is not limited to: receiving SLSS in subframe m on one or morecarriers according to an SLSS receiving rule; receiving downlink controlchannel or data channel in subframe m on one or more carriers accordingto a downlink receiving control behavior or a data channel receivingbehavior. The downlink control or data channel includes at least one of:

a PDCCH indicating a Random Access Response (RAR) and a PDSCH carryingthe RAR;

a Physical Broadcast Channel (PBCH);

a PDCCH indicating transmission of broadcast signaling, and a PDSCHbearing broadcast signaling; and

a PDSCH transmitted in a semi-persistent scheduling manner.

In addition, the first UE may exclude some candidate single-subframeresources from the candidate single-subframe set S according to thePSCCH detected in a channel detection window and an S-RSSI measured inthe channel detection window.

If the UE performs resource selection in subframe n, the UE may detectin subframes in the channel detection window before subframe n on eachcarrier of the carrier set C, the channel detection window may bedefined by specifications, e.g., subframes n−1000, n−999, . . . , aPDCCH indicating a Random Access Response (RAR) and a PDSCH carrying theRAR;

a Physical Broadcast Channel (PBCH);

a PDCCH indicating transmission of broadcast signaling, and a PDSCHbearing broadcast signaling; and

a PDSCH transmitted in a semi-persistent scheduling manner.

In addition, the first UE may exclude some candidate single-subframeresources from the candidate single-subframe set S according to thePSCCH detected in a channel detection window and an S-RSSI measured inthe channel detection window.

If the UE performs resource selection in subframe n, the UE may detectin subframes in the channel detection window before subframe n on eachcarrier of the carrier set C, the channel detection window may bedefined by specifications, e.g., subframes n−1000, n−999, . . . , n−1may be defined as a channel detection window. As to a subframe detectedby the first UE, the first UE measures the PSSCH-RSRP according to adecoded PSCCH and measures the S-RSSI of the subframe.

The first UE excludes the candidate single-subframe resources from theset S according to the following two steps.

Candidate single-subframe resource exclusion step 1:

If the first UE detects a PSCCH in subframe t_(m) ^(SL) in the channeldetection window on carrier c, c=0, 1, . . . , N1−1, and the value of apriority field in the PSCCH is prio_(RX), according to a resourcereservation indication, the PSCCH reserves the same frequency resourcesin subframe

t_(m + P_(rsvp _ RX))^(SL),

and the PSSCH-RSRP measured on the PSSCH scheduled by the PSCCH ishigher than a threshold Th_(prio) _(TX) _(,prio) _(RX) ^(c), whereinprio_(RX) denotes the value of the priority field in a subsequentlytransmitted PSCCH indicated by the higher layer of the UE, Th_(prio)_(TX) _(,prio) _(RX) ^(c) is configured by the eNB or is pre-configured,and denotes a threshold for the PSSCH-RSRP when the value of thepriority field of the subsequently transmitted PSCCH indicated by thehigher layer of the first UE is prio_(TX), whereas the measured priorityof the PSCCH is prio_(RX). Then:

If the set S is a single-carrier single-subframe resource set, for anysingle-carrier single-subframe resource R_(x,y) ^(c) in a subset SC ofthe set S, if there is a variable j∈{0, 1, . . . , C_(rexel)−1} whichmakes the single-subframe resource R_(x,y+j×P) _(rsvp_TX) ^(c) overlapwith reserved resources indicated in the PSCCH, wherein Cresel denotesthe number of times that resource is to be reserved after resourcereselection of the UE, P_(rsvp_TX) denotes the assumed resourcereservation period for determining the available candidatesingle-subframe resource indicated by higher layer of the UE, the firstUE excludes the single-subframe resource R_(x,y) ^(c) when performingresource selection or reselection, i.e., the first UE deletes thesingle-subframe resource R_(x,y) ^(c) from the set SC.

If the set S is a carrier-group single-subframe resource set, andcarrier c belongs to carrier group G, for any carrier-groupsingle-subframe resource R_(x) _(g) _(,y) ^(G) in subset SG in subsetj∈{0, 1, . . . , C_(rexel)−1} which makes the carrier-groupsingle-subframe resource

R_(x_(g), y + j × P_(rsvp _ TX))^(G)

overlap with the reserved resources indicated in the PSCCH, whereinCresel denotes the number of times that resource is to be reserved afterresource reselection of the UE, P_(rsvp_TX) denotes the assumed resourcereservation period for determining the available candidatesingle-subframe resource indicated by higher layer of the UE, the firstUE excludes the single-subframe resource R_(x) _(g) _(,y) ^(G) whenperforming resource selection or reselection, i.e., the first UE deletesthe single-subframe resource R_(x) _(g) _(,y) ^(G) from the set SG.

Candidate single-subframe resource exclusion step 2:

If the set S is a single-carrier single-subframe resource set, for anyremaining single-subframe resource R_(x,y) ^(c) in subset Sc of the setS, c=0, 1, . . . , N1−1, the first UE calculates an average value ofS-RSSI measured on subchannels x+k′ in subframe t_(y-P*j) ^(SL) in thechannel detection window, wherein j is an integer larger than 0, andK′=0, . . . , L_(subCH) ^(c)−1, P is a predetermined value, it may bedefined by specifications, configured by eNB or pre-configured, anddenotes S-RSSI average period, e.g., P=100 or an assumed resourcereservation period for determining available candidate single-subframeresources indicated by higher layer of the UE; the average value ofS-RSSI is noted by E_(x,y) ^(c). The first UE excludes 1−X2% resourceswith highest E_(x,y) ^(c) from the remaining single-subframe resourcesin set SC, wherein X2 is a predefined value, it may be defined byspecifications, or determined by the first UE according to configurationof the eNB, a pre-configuration or a current service type.

If the set S is a carrier-group single-subframe resource set, for anyremaining single-subframe resource R_(x) _(g) _(,y) ^(G) in subset SG ofset S, G=0, 1, . . . , R−1, the first UE calculates an average value ofS-RSSI measured on subchannels x+k′ on carrier gi in subframes t_(y-P*j)^(SL) in the channel detection window, wherein j is an integer largerthan 0, i=0, 1, . . . , M1−1 and k′=0, . . . , L_(subCH) ^(c)−1, P is apredetermined value, it may be defined by specifications, configured byeNB or pre-configured, and denotes S-RSSI average period, e.g., P=100 oran assumed resource reservation period for determining availablecandidate single-subframe resources indicated by higher layer of the UE;the average value of S-RSSI is noted by E_(x,y) ^(G) from the remainingsingle-subframe resources in set SG, wherein X2 is a predefined value,it may be defined by specifications, or determined by the first UEaccording to configuration of the eNB, a pre-configuration or a currentservice type.

At block S904, the first UE selects one or more single-subframeresources from the remaining single-subframe resources, and transmitsthe PSSCH on the selected resource.

If the set S is a single-carrier single-subframe resource set, i.e.carrier group is not configured, according to some embodiments of thepresent disclosure, the first UE may select only one single-carriersingle-subframe resource from the remaining single-carriersingle-subframe resources of the set S for data transmission. At thistime, the first UE may randomly select one single-carriersingle-subframe resource from the remaining single-carriersingle-subframe resources of the set S with equal probability, or, thefirst UE may randomly select a carrier c from all carriers in thecarrier set C with equal probability, and then randomly select asingle-carrier single-subframe resource with equal probability from theremaining single-carrier single-subframe resources of the set SC.

If the set S is a single-carrier single-subframe resource set, i.e.,carrier group is not configured, according to some embodiments of thepresent disclosure, the first UE may select multiple single-carriersingle-subframe resources from the remaining single-carriersingle-subframe resources of the set S for data transmission. At thistime, the first UE may randomly select multiple or all carriers withequal probability from the carriers in the carrier set C, and randomlyselect one single-carrier single-subframe resource with equalprobability from the remaining single-carrier single-subframe resourcesof each selected carrier.

If the set S is a single-carrier single-subframe resource set, i.e.carrier group is not configured, according to some embodiments of thepresent disclosure, the first UE may select multiple single-carriersingle-subframe resources from the remaining single-carriersingle-subframe resources of the set S for data transmission. At thistime, the first UE sorts the carriers in the carrier set C according totheir priorities or CBR, suppose that the order of the carriers is:carrier 0>carrier 1> . . . >carrier N1−1. Then, the first UE randomlyselect one single-carrier single-subframe resource with equalprobability from the remaining single-carrier single-subframe resourcesof carrier 0, and assume that the subframe where the selectedsingle-carrier single-subframe resource is located is t0; then, ifsubframe t0 has remaining single-carrier single-subframe resources oncarrier 1, the first UE randomly select one single-carriersingle-subframe resource from them with equal probability, if subframet0 does not have remaining single-carrier single-subframe resources oncarrier 1, the first UE randomly select one single-carriersingle-subframe resource from the remaining single-carriersingle-subframe resources of carrier 1, assume the subframe that thesingle-carrier single-subframe resource selected on carrier 1 is t1;thereafter, the first UE selects single-carrier single-subframeresources on other carriers following the same method.

If the set S is a single-carrier single-subframe resource set, i.e.carrier group is not configured, according to some embodiments of thepresent disclosure, the first UE may select multiple single-carriersingle-subframe resources from the remaining single-carriersingle-subframe resources of the set S. At this time, the first UEselects at most one single-carrier single-subframe resource on eachcarrier, and indexes of subframes where the single-carriersingle-subframe resource selected by the first UE are located have aminimum variance. If there are multiple selection manners with theminimum variance, the first UE may randomly select one of them withequal probability as the final selection.

If the set S is a single-carrier single-subframe resource set, i.e.carrier group is not configured, according to some embodiments of thepresent disclosure, the first UE randomly selects X1 single-carriersingle-subframe resources from the remaining single-carriersingle-subframe resources of each subset SC of the set S. Then, thefirst UE selects mc single-carrier single-subframe resources from the X1single-carrier single-subframe resources selected from each set Sc fortransmitting the PSSCH, wherein c=0, 1, . . . , N1−1, and mc=1 or 1.

If the set S is a carrier-group single-subframe resource set, i.e.,carrier group is configured, in some embodiments of the presentdisclosure, the first UE may select only one carrier-groupsingle-subframe resource from the remaining carrier-groupsingle-subframe resources of the set S for data transmission. At thistime, the first UE may randomly select one carrier-group single-subframeresource from the remaining carrier-group single-subframe resources ofthe set S; or, the first UE may randomly select a carrier group G withequal probability from all carrier groups of the carrier set C, and thenrandomly selects a carrier-group single-subframe resource with equalprobability from the remaining carrier-group single-subframe resourcesof the set SG.

If the set S is a carrier-group single-subframe resource set, i.e.,carrier group is configured, in some embodiments of the presentdisclosure, the first UE may select multiple carrier-groupsingle-subframe resources from the remaining carrier-groupsingle-subframe resources of the set S for data transmission. At thistime, the first UE may select at most one carrier-group single-subframeresource from each carrier group. The first UE may randomly selectmultiple carrier groups or all carrier groups with equal probabilityfrom the carrier groups of the carrier set C, and then randomly selectone carrier-group single-subframe resource with equal probability fromthe remaining carrier-group single-subframe resources of each selectedcarrier group.

It should be noted that, after the first UE performs the above resourceselection, the first UE will occupy the selected single-subframeresources for Y1 periodicities according to a particular resourcereservation period, wherein Y1 is a random value within a rangedetermined by higher layer of the UE, e.g., randomly determined by theMAC layer of the UE within 5˜15. When occupying the selectedsingle-subframe resources in the semi-persistent manner, if the size ofthe data packet transmitted by the first UE changes, the currentsingle-subframe resource may be unable to bear the new data packet evenif the highest allowable modulation level and code rate are adopted. Inthis situation, in some embodiments, the first UE may give up thecurrent selected single-subframe resource, and performs the blocks S901to S904 to reselect a single-subframe resource. Or, the first UE maykeep the currently selected single-subframe resource, and performs theabove blocks S901 to S904 to select an additional single-subframeresource on a carrier other than the carrier where the currentsingle-subframe resource is located.

The technical solution of the present disclosure is described in furtherdetail hereinafter with reference to detailed application scenarios andinteractions between devices to make the solution of the presentdisclosure clearer.

Embodiment 5

In embodiment 5, the multiple carriers on which the first UE performschannel detection and resource selection belong to one carrier group,i.e., the single-subframe resource is a carrier-group single-subframeresource. This embodiment includes the following operations.

At block S1001, the first UE determines a carrier set C available forresource selection or reselection.

In this embodiment, the carrier set C may include multiple carriers, andall carriers in the carrier set C belong to the same carrier group.Suppose that the number of carriers in the carrier set C is N. Thenumber and positions of the subframes used for SLSS transmission onrespective carrier are completely the same. Or, if the configuration ofthe subframes used for SLSS transmission is different on the N1carriers, all subframes used for SLSS transmission on the N1 carriersare not included in the resource pool.

At block S1002, the first UE determines a candidate single-subframeresource set S in the carrier set C.

In this embodiment, suppose that the UE performs resource selection orreselection in subframe n, the carriers in the carrier set C form acarrier group G, the carrier group G includes M carriers, then the UEdetermines L_(subCH) ^(g) ⁰ , L_(subCH) ^(g) ¹ , . . . and L_(subCH)^(g) ^(M1-1) may be zero. The set SG is the set S.

At block S1003, the first UE excludes some candidate single-subframeresources from the set S according to a channel detection result.

Suppose that the UE performs resource selection in subframe n. The UEmay detect in subframes of the channel detection window before subframen on each carrier of the carrier set C, wherein the channel detectionwindow is defined by specifications. For example, it may be defined thatsubframes n−1000, n−999, . . . , n−1 form the window detection window.As to the subframe detected by the first UE, the first UE measuresPSSCH-RSRP of the subframe according to the decoded PSCCH, and measuresS-RSSI of the subframe.

In this embodiment, the candidate single-subframe resource exclusionstep 1 may be performed as follows.

If the first UE detects PSCCH in subframe ti in the channel detectionwindow on carrier c, c=0, 1, . . . , N1−1, and the value of the priorityfield in the PSCCH is prio_(RX) according to a resource reservationindication, the PSCCH reserves the same frequency resources in subframe

t_(m + P_(rsvp _ RX))^(SL)

and value of the PSSCH-RSRP measured on the PSSCH scheduled by the PSCCHis greater than a specific threshold Th_(prio) _(TX) _(,prio) _(RX)^(c); wherein prio_(TX) denotes the value of the priority field in asubsequently transmitted PSCCH indicated by higher layer of the firstUE, Th_(prio) _(TX) _(,prio) _(RX) ^(c) is configured by the eNB or ispreconfigured, denoting a threshold value for the PSSCH-RSRP in the casethat the value of the priority field in the subsequently transmittedPSCCH on carrier c indicated by the higher layer of the first UE isprio_(TX), whereas the priority field of the detected PSCCH isprio_(RX). Then:

For any carrier-group single-subframe resource R_(x) _(g) _(,y) ^(G) inthe set S (i.e. SG), if there is a variable j∈{0, 1, . . . ,C_(rexel)−1} which makes the carrier-group single-subframe resourceR_(x) _(g) _(,y+j×P) _(rsvp_TX) ^(G) overlap with the reserved resourcesindicated in the PSCCH, wherein Cresel denotes the number of times thatresource is to be reserved after resource reselection of the UE,P_(rsvp_TX) denotes assumed resource reservation period for determiningavailable candidate single-subframe resources indicated by higher layerof the UE, the first UE deletes the single-subframe resource R_(x) _(g)_(,y) ^(G) from the set SG.

In this embodiment, the candidate single-subframe resource exclusionstep 2 may be performed as follows.

For a remaining single-subframe resource R_(x) _(g) _(,y) ^(G) in theset S (i.e., SG), G=0, 1, . . . , R−1, the first UE calculates anaverage value of the S-RSSI measured on subchannels x+k′ on carrier giin subframe t_(y-P*j) ^(SL) in the channel detection window, wherein jis an integer greater than 0, i=0, 1, . . . , M1−1, k′=0, . . . ,L_(subCH) ^(c)−1, P is a given value, which may be defined byspecifications, configured by the eNB or preconfigured and denotes theS-RSSI average period. For example P=100 or equals to the assumedresource reservation period for determining the available candidatesingle-subframe resources indicated by higher layer of the UE. The valueof the S-RSSI is denoted by E_(x,y) ^(G). The first UE excludes 1−X2%single-subframe resources with highest E_(x,y) ^(G) from the remainingsingle-subframe resources in the set SG. The value of X2 may be definedby specifications, or configured by the first UE according toinformation such as eNB configuration, a pre-configuration, a currentservice type, etc.

At block S1004, the first UE selects one or more single-subframeresources from the remaining single-subframe resources in the set S andtransmits the PSSCH on the selected resources.

In this embodiment, the first may randomly select one carrier-groupsingle-subframe resource with equal probability from the remainingcarrier-group single-subframe resources of the set S, and transmit thePSSCH using the selected carrier-group single-subframe resources.

If the UE needs to transmit signals on multiple carriers at a giventime, the signals include PSSCH, PSCCH and uplink signals, according tovarious embodiments of the present disclosure, the UE may adjust thetransmit power according to the following sequence.

Step 1, if the value of the priority field of the PSCCH transmitted bythe UE on one or more carriers is greater than or equal tothresSL-TxPrioritization, this means that the PSSCH transmitted by theUE on the one or more carriers carries V2X data with a priority lowerthan thresSL-TxPrioritization, wherein thresSL-TxPrioritization denotesa priority threshold which may be configured by the eNB orpreconfigured, the UE shall adjust the sidelink transmit power on one ormore carriers whose “priority” field has the value greater than or equalto thresSL-TxPrioritization, so as to make the total transmit power ofthe UE lower than an allowable maximum transmit power PCMAX of the UE.

Step 2, if the values of the “priority” fields of the PSCCH on allcurrent sidelink carriers of the UE are lower thanthresSL-TxPrioritization, or the total transmit power is still higherthan PCMAX after the UE adjusts the transmit power on all carriersmeeting the condition in step 1 to 0, and the UE transmits uplinksignals on one or more carriers, the UE shall adjust the transmit powerof the uplink signals on one or more carriers, so as to make the totaltransmit power of the UE lower than the allowed maximum transmit powerPCMAX of the UE.

Step 3, if the values of the “priority” fields of the PSCCH on allcurrent sidelink carriers of the UE are lower thanthresSL-TxPrioritization, and the UE does not transmit uplink signal onany carrier, the UE shall adjust the sidelink signal transmit power onthe carriers, so as to make the total transmit power of the UE lowerthan the allowed maximum transmit power PCMAX of the UE.

If the UE needs to transmit signals on multiple carriers at a giventime, according to another embodiment of the present disclosure, the UEadjust the transmit power following step 1 of block S1004: the UEdetermines the priority of the transmit signal on each carrier, adjustthe transmit power of one or more carriers used for transmitting datawith lowest priority, so as to make the total transmit power of the UElower than the allowed maximum transmit power PCMAX of the UE. If thetotal transmit power of the UE is still higher than PCMAX after thepower of the above carrier is adjusted to 0, the UE repeats step 1 ofblock S1004 for the remaining carriers until the total transmit power ofthe UE becomes lower than the allowed maximum transmit power PCMAX ofthe UE. The priority of the sidelink signal is determined by the valueof the “priority” field in the PSCCH of the sidelink signal. The higherthe value of the priority field, the lower the priority level. If thereare uplink signals, the priority of the uplink signals is higher thanthe sidelink signal with priority value thresSL-TxPrioritization, butlower than the sidelink signal with priority valuethresSL-TxPrioritization−1, thresSL-TxPrioritization denotes a prioritythreshold which may be configured by the eNB or preconfigured,thresSL-TxPrioritization−1 denotes thresSL-TxPrioritization minus 1.

Embodiment 6

In embodiment 6, the multiple carriers on which the first UE performschannel detection and resource selection belong to multiple carriergroups. For example, one or more carriers belonging to the samefrequency band in carrier set C belong to the same carrier group. Atthis time, the single-subframe resource is a carrier-groupsingle-subframe resource. This embodiment includes the followingoperations.

At block S1101, the first UE determines a carrier set C available forresource selection or reselection.

In this embodiment, the carrier set C includes multiple carriers, andthe carriers in the carrier set C belong to multiple carrier groups.Assume that the number of carriers in the carrier group C is N1, the N1carriers respectively belongs to R carrier groups, and the number andpositions of subframes used for SLSS transmission are completely thesame on the carriers within each carrier group. Or, the SLSStransmission subframes may be configured differently on the carrierswithin each carrier group, but all of the SLSS transmission subframes onthe carriers within the carrier group are not used for configuring theresource pool.

At block S1102, the first UE determines a candidate single-subframeresource set S in the carrier set C.

In this embodiment, suppose that the UE performs resource selection orreselection in subframe n, for any carrier group G in the carrier set C,the UE determines L_(subCH) ^(g) ⁰ , L_(subCH) ^(g) ¹ , . . . ,L_(subCH) ^(g) ^(M1-1) continuous subchannels respectively on carriersg0, g1, . . . , gM1−1 in any subframe belonging to the resource pool andwithin [n+T1, n+T2] on the carrier group G as the candidatesingle-subframe resources, wherein T1 and T2 are subjected to theimplementation of the UE. The total number of single-subframe resourceson carrier group G is denoted by M_(total) ^(G), the M_(total) ^(G)candidate single-subframe resources constitute a set SG. It should benoted that, L_(subCH) ^(g) ⁰ , L_(subCH) ^(g) ¹ , . . . , L_(subCH) ^(g)^(M1-1) are determined by higher layer of the UE, e.g., MAC layer of theUE, and one or more of them may be zero. The union of the sets SG of allcarrier groups forms the set S.

At block S1103, the first UE excludes some candidate single-subframeresources from the set S according to a channel detection result.

Suppose that the UE performs resource selection in subframe n. The UEmay detect in subframes of the channel detection window before subframen on each carrier of the carrier set C, wherein the channel detectionwindow is defined by specifications. For example, it may be defined thatsubframes n−1000, n−999, . . . , n−1 form the window detection window.As to a subframe detected by the first UE, the first UE measuresPSSCH-RSRP of the subframe according to a decoded PSCCH, and measuresS-RSSI of the subframe.

In this embodiment, the candidate single-subframe resource exclusionstep 1 may be performed as follows.

If the first UE detects a PSCCH in subframe t_(m) ^(SL) in the channeldetection window on carrier c, c=0, 1, . . . , N1−1, and the value ofthe priority field in the PSCCH is prio_(RX), according to a resourcereservation indication, the PSCCH reserves the same frequency resourceon subframe t_(m+P) _(rsvp_RX) ^(SL), and value of the PSSCH-RSRPmeasured on the PSSCH scheduled by the PSCCH is greater than a specificthreshold Th_(prio) _(TX) _(,prio) _(RX) ^(c); wherein prio_(TX) denotesthe value of the priority field in a subsequently transmitted PSCCHindicated by higher layer of the first UE, Th_(prio) _(TX) _(,prio)_(RX) ^(c) is configured by the eNB or is preconfigured, denoting athreshold value for the PSSCH-RSRP in the case that the value of thepriority field in the subsequently transmitted PSCCH on carrier cindicated by the higher layer of the first UE is prio_(TX), whereas thepriority field of the detected PSCCH is prio_(RX). Then:

If carrier c belongs to carrier group G, for any carrier-groupsingle-subframe resource R_(x) _(g) _(,y) ^(G) in the set SG of thecarrier group G, if there is a variable j∈{0, 1, . . . , C_(rexel)−1}which makes the carrier-group single-subframe resource

R_(x_(g), y + j × P_(rsvp _ TX))^(G)

overlap with the reserved resource indicated in the PSCCH, whereinCresel denotes the number of times that resource is to be reserved afterresource reselection of the UE, P_(rsvp_TX) denotes an assumed resourcereservation period for determining available candidate single-subframeresources indicated by higher layer of the UE, the first UE deletes thesingle-subframe resource R_(x) _(g) _(,y) ^(G) from the set SG.

In this embodiment, the candidate single-subframe resource exclusionstep 2 may be performed as follows.

For a remaining single-subframe resource R_(x) _(g) _(,y) ^(G) in theset SG, G=0, 1, . . . , R−1, the first UE calculates an average value ofS-RSSI measured on subchannels x+k′ on carrier gi in subframe t_(y-P*j)^(SL) in the channel detection window, wherein j is an integer greaterthan 0, i=0, 1, . . . , M1−1, k′=0, . . . , L_(subCH) ^(g) ¹ −1, P is aspecific value, which may be defined by specifications, configured bythe eNB or preconfigured and denotes the S-RSSI average period. Forexample P=100 or equals to the assumed resource reservation period fordetermining the available candidate single-subframe resources indicatedby higher layer of the UE. The value of the S-RSSI is denoted by E_(x,y)^(G). The first UE excludes 1−X2% single-subframe resources with highestE_(x,y) ^(G) from the remaining single-subframe resources in the set SG.The value of X2 may be defined by specifications, or configured by thefirst UE according to information such as eNB configuration, apre-configuration, a current service type, etc.

At block S1104, the first UE selects one or more single-subframeresources from the remaining single-subframe resources in the set S andtransmits the PSSCH on the selected resources.

In this embodiment, the first UE may randomly select one carrier-groupsingle-subframe resource for PSSCH transmission from the remainingcarrier-group single-subframe resources of set SG of each of the Rcarrier groups of the carrier set C, G=0, 1, . . . R−1. The manner thatthe first UE randomly selects the resource from the remainingsingle-subframe resources of SGshould ensure that each remainingsingle-subframe resource has the same probability to be selected.

If the UE needs to transmit signals on multiple carriers at a giventime, the signals include PSSCH, PSCCH and uplink signals, according tovarious embodiments of the present disclosure, the UE may adjust thetransmit power according to the following sequence.

Step 1, if the value of the priority field of the PSCCH transmitted bythe UE on one or more carriers is greater than or equal tothresSL-TxPrioritization, this means that the PSSCH transmitted by theUE on the one or more carriers carries V2X data with a priority lowerthan thresSL-TxPrioritization, wherein thresSL-TxPrioritization denotesa priority threshold which may be configured by the eNB orpreconfigured, the UE may adjust the sidelink transmit power on one ormore carriers whose “priority” field has a value greater than or equalto thresSL-TxPrioritization, so as to make the total transmit power ofthe UE lower than an allowable maximum transmit power PCMAX of the UE.

Step 2, if the values of the “priority” fields of the PSCCH on allcurrent sidelink carriers of the UE are lower thanthresSL-TxPrioritization, or the total transmit power is still higherthan PCMAX after the UE adjusts the transmit power on all carriersmeeting the condition in step 1 to 0, and the UE transmits uplinksignals on one or more carriers, the UE may adjust the transmit power ofthe uplink signals on one or more carriers, so as to make the totaltransmit power of the UE lower than the allowed maximum transmit powerPCMAX of the UE.

Step 3, if the values of the “priority” fields of the PSCCH on allcurrent sidelink carriers of the UE are lower thanthresSL-TxPrioritization, and the UE does not transmit uplink signal onany carrier, the UE may adjust the sidelink signal transmit power on thecarriers, so as to make the total transmit power of the UE lower thanthe allowed maximum transmit power PCMAX of the UE.

If the UE needs to transmit signals on multiple carriers at a giventime, according to another embodiment of the present disclosure, the UEadjust the transmit power following step 1 of block S1004: the UEdetermines the priority of the transmit signal on each carrier, adjustthe transmit power of one or more carriers used for transmitting datawith lowest priority, so as to make the total transmit power of the UElower than the allowed maximum transmit power PCMAX of the UE. If thetotal transmit power of the UE is still higher than PCMAX after thepower of the above carrier(s) is adjusted to 0, the UE repeats step 1 ofblock S1004 for the remaining carriers until the total transmit power ofthe UE becomes lower than the allowed maximum transmit power PCMAX ofthe UE. The priority of the sidelink signal is determined by the valueof the “priority” field in the PSCCH of the sidelink signal. The higherthe value of the priority field, the lower the priority level. If thereare uplink signals, the priority of the uplink signals is higher thanthe sidelink signal with priority value thresSL-TxPrioritization, butlower than the sidelink signal with priority valuethresSL-TxPrioritization−1, thresSL-TxPrioritization denotes a prioritythreshold which may be configured by the eNB or preconfigured,thresSL-TxPrioritization−1 denotes thresSL-TxPrioritization minus 1.

If the UE needs to transmit signals on multiple carriers simultaneously,the signals include PSSCH, PSCCH and uplink signals, if the number ofcarriers on which the UE needs to transmit signals is greater than thenumber of current available radio transmission chains of the UE, the UEprioritizes the transmission of signals with high priorities and givesup the transmission of signals with low priorities. If the UE needs totransmit signals on two or more carriers at a given time, the signalsinclude PSSCH, PSCCH and uplink signals, and the UE does not supportsimultaneous transmission on the multiple carriers, the UE prioritizesthe transmission of the signals with high priority and gives up thetransmission of the signals with low priority. The priority of thesidelink signal is determined by the value of the “priority” field inthe PSCCH of the sidelink signal. The higher the value of the priorityfield, the lower the priority level. If there are uplink signals, thepriority of the uplink signals is higher than the sidelink signal withpriority value thresSL-TxPrioritization, but lower than the sidelinksignal with priority value thresSL-TxPrioritization−1,thresSL-TxPrioritization denotes a priority threshold which may beconfigured by the eNB or preconfigured, thresSL-TxPrioritization−1denotes thresSL-TxPrioritization minus 1.

Embodiment 7

In embodiment 7, the carrier set C on which the first UE performschannel detection and resource selection is not configured with carriergroup, i.e., the single-subframe resource is single-carriersingle-subframe resource. This embodiment includes the followingoperations.

At block S1201, the first UE determines a carrier set C available forresource selection or reselection.

In this embodiment, the carrier set C includes multiple carriers, thenumber of carriers in the carrier group C is N. The number and positionsof subframes used for SLSS transmission are completely the same on thecarriers in the carrier set C. Or, the SLSS transmission subframes maybe configured differently on the carriers in the carrier set C, but allof the SLSS transmission subframes on the N1 carriers are not used forconfiguring the resource pool.

At block S1202, the first UE determines a candidate single-subframeresource set S in the carrier set C.

In this embodiment, it is defined that a single-subframe resourceR_(x,y) ^(c) on any carrier c in the carrier set C includes L_(subCH)^(c) continuous subchannels starting from subchannel x in subframe t_(y)^(SL), wherein y denotes a relative index of subframe t_(y) ^(SL) in theresource pool, L_(subCH) ^(c) is determined by higher layer (such as MAClayer) of the UE, and denotes the number of subchannels for one PSSCHtransmission on carrier c, c=0, 1, . . . , N1−1. If the UE performsresource selection or reselection in subframe n, the UE may determinethe L_(subCH) ^(c) continuous subchannels in any subframe belonging tothe resource pool and within [n+T1, n+T2] on carrier c as a candidatesingle-subframe resource, wherein T1 and T2 are subjected to theimplementation of the UE. The total number of single-subframe resourceson carrier c is noted by M_(total) ^(c), the M_(total) ^(c) candidatesingle-subframe resources form a set SC. A union of the single-carriersingle-subframe resource sets of all carriers in carrier set C is theset S.

At block S1203, the first UE excludes some candidate single-subframeresources from the set S according to a channel detection result.

If the UE performs resource selection in subframe n, the UE may performdetection in subframes within the channel detection window beforesubframe n on each carrier of the carrier set C, wherein the channeldetection window may be defined by specifications, e.g., the channeldetection window may include subframes n−1000, n−999, . . . , n−1. For asubframe detected by the first UE, the first UE measures PSCCH-RSPR ofthe subframe according to a decoded PSCCH, and measures the S-RSSI ofthe subframe.

In this embodiment, the candidate single-subframe resource exclusionstep 1 may include following operations:

If the first UE detects a PSCCH in subframe t_(m) ^(SL) in the channeldetection window on carrier c, c=0, 1, . . . , N1−1, and the value ofthe priority field in the PSCCH is prio_(RX), according to the resourcereservation indication, the PSCCH reserves the same frequency resourcein subframe

t_(m + P_(rsvp _ RX))^(SL),

and the value of the PSSCH-RSRP measured on the PSSCH scheduled by thePSCCH is greater than a specific threshold Th_(prio) _(TX) _(,prio)_(RX) ^(c); wherein prio_(TX) denotes the value of the priority field ina subsequently transmitted PSCCH indicated by higher layer of the firstUE, Th_(prio) _(TX) _(,prio) _(RX) ^(c) is configured by the eNB or ispreconfigured, denoting a threshold value for the PSSCH-RSRP in the casethat the value of the priority field in the subsequently transmittedPSCCH on carrier c indicated by the higher layer of the first UE isprio_(TX), whereas the priority field of the detected PSCCH isprio_(RX). Then:

For any single-carrier single-subframe resource R_(x,y) ^(c) in thesubset SC of the set S, if there is a variable j∈{0, 1, . . . ,C_(rexel)−1} which makes the single-subframe resource

R_(x, y + j × P_(rsvp _ TX))^(c)

overlap with reserved resource indicated in the PSCCH, wherein Creseldenotes the number of times that resource is to be reserved afterresource reselection of the UE, P_(rsvp_TX) denotes the assumed resourcereservation period for determining the available candidatesingle-subframe resource indicated by higher layer of the UE, the firstUE excludes the single-subframe resource R_(x,y) ^(c) when performingresource selection or reselection, i.e., the first UE deletes thesingle-subframe resource R_(x,y) ^(c) from the set SC.

In this embodiment, the candidate single-subframe resource exclusionstep 2 is performed as follows.

For any remaining single-subframe resource R_(x,y) ^(c) in subset SC ofthe set S, c=0, 1, . . . , N1−1, the first UE calculates an averagevalue of S-RSSI measured on subchannels x+k′ in subframe t_(y-P*j) ^(SL)in the channel detection window, wherein j is an integer larger than 0,and k′=0, . . . , L_(subCH) ^(c)−1, P is a predetermined value, it maybe defined by specifications, configured by eNB or pre-configured, anddenotes S-RSSI average period, e.g., P=100 or an assumed resourcereservation period for determining available candidate single-subframeresources indicated by higher layer of the UE; the average value ofS-RSSI is noted by E_(x,y) ^(c). The first UE excludes 1−X2% resourceswith highest E_(x,y) ^(c). from the remaining single-subframe resourcesin set SC, wherein X2 is a predefined value, it may be defined byspecifications, or determined by the first UE according to configurationof the eNB, a pre-configuration or a current service type.

At block S1204, the first UE selects one or more single-subframeresources from the remaining single-subframe resources of the set S, andtransmits PSSCH on the selected resources.

In this embodiment, the first UE selects multiple single-subframeresources for PSSCH transmission from the remaining single-subframeresources of set S. The first UE may select the multiple single-subframeresources via any one of the following manners.

Manner 1: the UE randomly selects multiple carriers in the carrier set Cwith equal probability or selects all carriers of the carrier set C, andrandomly selects one single-carrier single-subframe resource from theremaining single-carrier single-subframe resources of each selectedcarrier with equal probability.

Manner 2: the first UE sorts the carriers in the carrier set C accordingto their priorities or CBR. Suppose that the carriers are sorted as:carrier 0>carrier 1> . . . >carrier N1−1. Then, the first UE randomlyselects one single-carrier single-subframe resource from the remainingsingle-carrier single-subframe resources of carrier 0. It is assumedthat the subframe where the selected single-carrier single-subframeresource is located is subframe t0. Then, if there is remainingsingle-carrier single-subframe resource in subframe t0 on carrier 1, thefirst UE randomly selects one single-carrier single-subframe resourcefrom subframe t0. If there is no remaining single-carriersingle-subframe resource in subframe t0 on carrier 1, the first UErandomly selects a single-carrier single-subframe resource from theremaining single-carrier single-subframe resources of carrier 1. Supposethat the single-carrier single-subframe resource selected on carrier 1is t1. Then, the first UE selects single-carrier single-subframeresources on other carriers following the same method.

Manner 3: the first UE selects at most one single-carriersingle-subframe resource on each carrier, and the indexes of thesubframes where the single-carrier single-subframe resources finallyselected by the first UE has a minimum variance, if there are multipleselections with the minimum variance, the first UE may randomly selectone of them as the final selection.

Manner 4: the first UE randomly selects X1 single-carriersingle-subframe resources with equal probability from the remainingsingle-carrier single-subframe resources of each subset SC of the set S,and the first UE selects mc single-carrier single-subframe resources forPSSCH transmission from the X1 single-carrier single-subframe resourcesof each SC, wherein c=0, 1, . . . , N1−1, mc=0 or 1, i.e., the UE mayselect at most one single-carrier single-subframe resource on thecarrier or do not select any resource,

${{\sum\limits_{c = 0}^{N - 1}m_{c}} = M};$

the value of X1 may be directly configured by the eNB or directlypreconfigured, or directly defined by specifications, or indirectlyconfigured by the eNB or indirectly preconfigured, or indirectly definedby specifications, e.g., X1=┌0.1*R_(S)┐, wherein RS denotes the totalnumber of resources in the set S. The method for selecting the misingle-carrier single-subframe resources from the X1 single-carriersingle-subframe resources of carrier Ci may be determined according tothe implementation of the UE. In some embodiments, the method that thefirst UE selects the mi single-carrier single-subframe resources is ableto ensure that the radio transmission capability of the first UE cansupport the PSSCH transmission on the mi single-carrier single-subframeresources. On the premise of this, the method that the first UE selectsthe mi single-carrier single-subframe resources shall minimize thehalf-duplex restriction between the single-carrier single-subframeresources.

If the UE needs to transmit signals on multiple carriers at a giventime, the signals include PSSCH, PSCCH and uplink signals, according tovarious embodiments of the present disclosure, the UE may adjust thetransmit power according to the following sequence.

Step 1, if the value of the priority field of the PSCCH transmitted bythe UE on one or more carriers is greater than or equal tothresSL-TxPrioritization, this means that the PSSCH transmitted by theUE on the one or more carriers carries V2X data with a priority lowerthan thresSL-TxPrioritization, wherein thresSL-TxPrioritization denotesa priority threshold which may be configured by the eNB orpreconfigured, the UE may adjust the sidelink transmit power on one ormore carriers whose “priority” field has a value greater than or equalto thresSL-TxPrioritization, so as to make the total transmit power ofthe UE lower than an allowable maximum transmit power PCMAX of the UE.

Step 2, if the values of the “priority” fields of the PSCCH on allcurrent sidelink carriers of the UE are lower thanthresSL-TxPrioritization, or the total transmit power is still higherthan PCMAX after the UE adjusts the transmit power on all carriersmeeting the condition in step 1 to 0, and the UE transmits uplinksignals on one or more carriers, the UE may adjust the transmit power ofthe uplink signals on one or more carriers, so as to make the totaltransmit power of the UE lower than the allowed maximum transmit powerPCMAX of the UE.

Step 3, if the values of the “priority” fields of the PSCCH on allcurrent sidelink carriers of the UE are lower thanthresSL-TxPrioritization, and the UE does not transmit uplink signal onany carrier, the UE may adjust the sidelink signal transmit power on thecarriers, so as to make the total transmit power of the UE lower thanthe allowed maximum transmit power PCMAX of the UE.

If the UE needs to transmit signals on multiple carriers at a giventime, according to another embodiment of the present disclosure, the UEadjust the transmit power following step 1 of block 204: the UEdetermines the priority of the transmit signal on each carrier, adjustthe transmit power of one or more carriers used for transmitting datawith lowest priority, so as to make the total transmit power of the UElower than the allowed maximum transmit power PCMAX of the UE. If thetotal transmit power of the UE is still higher than PCMAX after thepower of the above carrier is adjusted to 0, the UE repeats step 1 ofblock 204 for the remaining carriers until the total transmit power ofthe UE becomes lower than the allowed maximum transmit power PCMAX ofthe UE. The priority of the sidelink signal is determined by the valueof the “priority” field in the PSCCH of the sidelink signal. The higherthe value of the priority field, the lower the priority level. If thereare uplink signals, the priority of the uplink signals is higher thanthe sidelink signal with priority value thresSL-TxPrioritization, butlower than the sidelink signal with priority valuethresSL-TxPrioritization−1, thresSL-TxPrioritization denotes a prioritythreshold which may be configured by the eNB or preconfigured,thresSL-TxPrioritization−1 denotes thresSL-TxPrioritization minus 1.

If the UE needs to transmit signals on multiple carriers at a giventime, the signals include PSSCH, PSCCH and uplink signals, if the numberof carriers on which the UE needs to transmit signals is greater thanthe number of current available radio transmission chains of the UE, theUE prioritizes the transmission of signals with high priorities andgives up the transmission of signals with low priorities. If the UEneeds to transmit signals on two or more carriers at a given time, thesignals include PSSCH, PSCCH and uplink signals, and the UE does notsupport simultaneous transmission on the multiple carriers, the UEprioritizes the transmission of the signals with high priority, andgives up the transmission of the signals with low priority. The priorityof the sidelink signal is determined by the value of the “priority”field in the PSCCH of the sidelink signal. The higher the value of thepriority field, the lower the priority level. If there are uplinksignals, the priority of the uplink signals is higher than the sidelinksignal with priority value thresSL-TxPrioritization, but lower than thesidelink signal with priority value thresSL-TxPrioritization−1,thresSL-TxPrioritization denotes a priority threshold which may beconfigured by the eNB or preconfigured, thresSL-TxPrioritization−1denotes thresSL-TxPrioritization minus 1.

FIG. 11 is a block diagram illustrating a UE for executing the resourceselection or reselection method in V2X communication according tovarious embodiments of the present disclosure. As shown in FIG. 11, theUE includes: a candidate time-frequency resource determining module1130, a resource selection or reselection module 1132, and atransmitting module 1133.

The candidate time-frequency resource determining module is to determineone or more carriers on which the UE performs channel detection, if acarrier group is configured, determine the number of the carrier groupsand the number of carriers included in each carrier group; and todetermine a candidate single-subframe resource set for each carrier oreach carrier group;

the resource selection or reselection module is to select one or moresingle-subframe resources for data transmission from the candidatesingle-subframe resource set; and

the transmitting module is to transmit a PSSCH on the selected one ormore single-subframe resources.

In some embodiments, the UE as shown in FIG. 11 may further include aresource detecting module 1131, to exclude some candidatesingle-subframe resources from the candidate single-subframe resourcesaccording to a PSCCH detected in a channel detection window and anS-RSSI measured in the channel detection window, or exclude somecandidate single-subframe resources from the candidate single-subframeresources according another method described in block S1101. In thiscase, the resource selection or reselection module is to select, afterthe channel detecting module performs the exclusion operation to thecandidate single-subframe resources, one or more single-subframeresources for data transmission from the remaining single-subframeresources.

Those skilled in the art may understand that the present disclosurecomprises devices for performing one or more of the operations in thepresent application. These devices may be specially designed andmanufactured for required objectives, or may also comprise known devicesin a general-purpose computer. These devices have computer programsstored therein, and these computer programs are selectively activated orreconstructed. Such computer programs may be stored in a device (e.g.computer) readable medium or stored in any type of medium that issuitable for storing an electronic instruction and respectively coupledto a bus. The computer readable medium comprises but is not limited toany type of disk (comprising a floppy disk, hard disk, optical disc,CD-ROM and magnetic optical disc), ROM (Read-Only Memory), RAM (RandomAccess Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM(Electrically Erasable Programmable Read-Only Memory), flash memory,magnetic card or light card. That is, the readable medium comprises anymedium that a device (e.g. computer) stores or transmits information ina readable form.

Those skilled in the art may understand that computer programinstructions may be used to implement each block in these structuraldiagrams and/or block diagrams and/or flow charts and combinations ofblocks of these structural diagrams and/or block diagrams and/or flowcharts. Those skilled in the art may understand that these computerprogram instruction may be provided to a general-purpose computer, aspecialized computer or a processor of other programmable dataprocessing methods, so as to perform solutions specified in a block ormultiple blocks in structural diagrams and/or block diagrams and/or flowcharts disclosed in the present disclosure by a computer or a processorof other programmable data processing methods.

Those skilled in the art may understand that the steps, measures andsolutions in various operations, methods and flows which have beendiscussed in the present disclosure may be alternated, altered, combinedor deleted. Furthermore, other steps, measures and solutions in variousoperations, methods and flows which have been discussed in the presentdisclosure may also be alternated, altered, rearranged, decomposed,combined or deleted. Furthermore, the steps, measures and solutions invarious operations, methods and flows disclosed in the presentdisclosure in the prior art may also be alternated, altered, rearranged,decomposed, combined or deleted.

What have been described above are merely some implementations of thepresent disclosure. It should be noted that for those of ordinary skillsin the art, several improvements and polishments may also be madewithout departing from the principle of the present disclosure, andthese improvements and polishments should also be deemed as the scope ofprotection of the present disclosure.

1. A resource selection method performed by a user equipment (UE) invehicle to everything (V2X) communication, which comprises the steps of:detecting physical sidelink control channel (PSCCH) transmitted by otherUE(s); selecting (a) single-subframe resource(s) from single-subframeresources which do not overlap with single-subframe resources reservedby the detected PSCCH; and transmitting physical sidelink shared channel(PSSCH) on the selected single-subframe resource(s).
 2. The resourceselection or reselection method as claimed in claim 1, wherein selecting(a) single-subframe resource(s) from single-subframe resources which donot overlap with single-subframe resources reserved by the detectedPSCCH further comprises: measuring sidelink reference signal receivedpower of PSSCH (PSSCH-RSRP) scheduled by the detected PSCCH; and if thePSSCH-RSRP is higher than a particular threshold, then selecting (a)single-subframe resource(s) from single-subframe resources which do notoverlap with single-subframe resources reserved by the detected PSCCH;or if the detected PSCCH is in a particular format, then selecting (a)single-subframe resource(s) from single-subframe resources which do notoverlap with single-subframe resources reserved by the detected PSCCH;or if value of a priority field contained in the detected PSCCH isgreater than a particular value, then selecting (a) single-subframeresource(s) from single-subframe resources which do not overlap withsingle-subframe resources reserved by the detected PSCCH.
 3. Theresource selection or reselection method as claimed in claim 1, whereinPSCCH transmitted by other UE(s) is detected on part of PSCCH resourcesin a currently selected transmitting resource pool; and wherein the UEdetermines positions of the part of PSCCH resources by receivingsignalling from an evolved Node B.
 4. A resource allocation methodperformed by UE in sidelink communications, comprising: determining aSideLink Grant (SLG); wherein the SLG includes position information of MPSSCH transmission resources, the M PSSCH transmission resources areused for M times of transmission of one Transmission Block (TB), M is apositive integer; and the first UE transmitting a PSSCH according to thedetermined SLG.
 5. The method of claim 4, wherein the determining theSLG further comprises: determining the SLG according to one or moredownlink control signaling transmitted by a base station; or determiningthe SLG through performing a detection in a channel detection window. 6.The method of claim 4, wherein the M PSSCH transmission resources have abinding relationship between thereof; determining the SLG furthercomprises: determining a resource pattern of the SLG according todownlink control signaling transmitted by a base station; or,determining a resource pattern of the SLG according to the detectionperformed in a channel detection window; wherein the resource patternincludes M PSSCH transmission resource units in a predefined resourcepattern space, and is used for indicating the position information ofthe PSSCH time-frequency resources for the M times transmission of theTB; a first PSSCH transmission resource unit and a last PSSCHtransmission resource unit contained in each resource pattern have atime-domain gap less than or equal to a sum of a maximum tolerated delayfor data transmission of the first UE and the time required for encodingthe PSSCH.
 7. The method of claim 4, wherein after determining the SLGand before the first UE transmitting the PSSCH according to thedetermined SLG, the method further comprises: determining an occupationmanner of the SLG; wherein the transmitting the PSSCH according to thedetermined SLG comprises: the first UE transmitting the PSSCH accordingto the SLG based on the determined occupation manner.
 8. The method ofclaim 4, wherein at least one of: when the first UE occupies the SLGsemi-persistently according to a predefined period, the SLG furtherincludes a period length of the semi-persistent occupation; or whenthere is no binding relationship between the PSSCH time-frequencyresources and PSCCH resources scheduling the PSSCH, one or more downlinkcontrol signaling include position information of transmission resourcesof the PSCCH.
 9. The method of claim 4, further comprising: the first UEdetermining a modulation and coding scheme for transmitting the TB. 10.A resource selection method performed by UE in Vehicle to everything(V2X) communication, comprising: determining a carrier set C availablefor resource selection or reselection; determining a candidatesingle-subframe resource set S in the carrier set C; and selecting atleast one single-subframe resource from the set S, and transmitting asidelink data channel on the selected resource.
 11. The method of claim10, wherein the carrier set C includes at least one carrier; if thecarrier set C includes at least two carriers, a configuration ofSidelink Synchronization Signal (SLSS) transmission subframes on the atleast two carriers are the same; or, if the carrier set C includes atleast two carriers, the configuration of the SLSS transmission subframeson the at least two carriers are different, and if subframe x is one ofthe SLSS transmission subframes on any of the at least two carriers,subframe x on each of the at least two carriers is not used forconfiguring a resource pool; or, if the carrier set C includes at leasttwo carriers, for each of some or all of the at least two carriers, theSLSS transmission subframes and resource pool are configuredindependently.
 12. The method of claim 10, wherein the determining thecandidate single-subframe resource set S in the carrier set C comprises:determining that a single-subframe resource R_(x,y) ^(c) on any carrierc in the carrier set C includes L_(subCH) ^(c) continuous sub-channelsstarting from sub-channel x in subframe t_(y) ^(SL), wherein y denotes arelative index of subframe t_(y) ^(SL) in a resource pool; L_(subCH)^(c) denotes a number of sub-channels used for one PSSCH transmission oncarrier c, c=0, 1, . . . , N1−1; if the UE performs resource selectionor reselection in subframe n, L_(subCH) ^(c) continuous sub-channels inany subframe belonging to the resource pool and within [n+T₁,n+T₂] oncarrier c are candidate single-subframe resources, wherein thedetermination of T₁ and T₂ are subject to the implementation of the UE;a total number of single-subframe resources on carrier c is denoted byM_(total) ^(c) the M_(total) ^(c) candidate single-subframe resourcesconstitute a set S^(C), a union of single-carrier single-subframeresource sets of carriers in the carrier set C is the candidatesingle-subframe resource set S, wherein the single-carriersingle-subframe resource is a single-subframe resource of which allsubchannels are located on the same carrier.
 13. The method of claim 10,wherein the UE selecting the at least one single-subframe resource inthe set S via any one of: selecting one single-carrier single-subframeresource for data transmission in the set S, wherein the UE randomlyselecting one single-carrier single-subframe resource with equalprobability from the set S; or, the UE randomly selecting a carrier cwith equal probability from all carriers in the carrier set C, andrandomly selecting one single-carrier single-subframe resource withequal probability from a set S^(C); selecting at least twosingle-carrier single-subframe resources for data transmission in theset S, wherein the UE randomly selecting multiple carriers or selectingall carriers with equal probability in the carrier set C, and randomlyselecting one single-carrier single-subframe resource with equalprobability from the single-carrier single-subframe resources of eachselected carrier; selecting at least two single-carrier single-subframeresources for data transmission in the set S, wherein the UE sorting thecarriers in the carrier set C according to their priorities or ChannelBusy Ratio (CBR), denoting the order of carriers by carrier 0>carrier 1>. . . >carrier N1−1, the UE randomly selecting one single-carriersingle-subframe resource with equal probability from the single-carriersingle-subframe resources of carrier 0, the subframe where the selectedsingle-carrier single-subframe resource is located is denoted by t0, ifsubframe t0 contains single-carrier single-subframe resource on carrier1, the UE randomly selecting one single-carrier single-subframe resourcefrom them with equal probability, if the subframe t0 does not containsingle-carrier single-subframe resource on carrier 1, the UE randomlyselecting one single-carrier single-subframe resource with equalprobability from a single-carrier single-subframe resource set ofcarrier 1, and the UE repeating the process to select the single-carriersingle-subframe resources on other carriers; selecting multiplesingle-carrier single-subframe resources for data transmission in theset S, wherein the UE selecting at most one single-carriersingle-subframe resource on each carrier, and indexes of subframes wherethe single-carrier single-subframe resources selected by the UE arelocated have a minimum variance, if there are multiple selections withthe minimum variance, the UE randomly selecting one of the selections;randomly selecting X1 single-carrier single-subframe resources withequal probability from remaining single-carrier single-subframeresources of each subset S^(C) of the set S, and the UE selecting mesingle-carrier single-subframe resources for transmitting a physicalsidelink shared channel (PSSCH) from X1 single-carrier single-subframeresources selected from each set S^(C), wherein c=0, 1, . . . , N1−1 andm_(c)=0 or
 1. 14. The method of claim 10, wherein before selecting theat least one single-subframe resource in the set S, the method furthercomprises: if the UE is to perform a receiving operation in at least onesubframe after subframe n on at least one carrier, the UE excluding oneor more candidate single-subframe resources which overlap or conflictwith the at least one subframe from the set S.
 15. (canceled)